Последний блок

3 436 243

Время после блока

82 часов

49 минут

58 секунд

7 084

Новых транзакций

133.40

ś/vByte

Лучшая комиссия

Bitcoin testnet faucet

tBTC Onetime limit 0.01 tBTC

Транзакция

Bitcoin testnet транзакция 9d830dc2708284bec95126db2b3b32252c999fdd92406609d26720fe84699e8b

Время	2023-02-17 18:54:44 UTC 1year 9months ago
Блок	2420426 [23]
Тип	segwit
Подтверждений	1 015 818
Время подтверждения	less then minute
Размер / базовый размер	6497 / 3178 bytes
Виртуальный размер / вес	4008 / 16031

Witness хеш	1f280321ea683ea3bfd8a56795fb0ea2d0c7219b1d14db706378dd67a7e304a4
Версия	2
Lock time	0
Комиссия	0.00004310tBTC
Уровень комиссии	1.08 satoshi/vByte
	Сырая транзакция

Схема

31 входов	0.07067780tBTC

	2NFhFQgR1tgb2iFwHHrFiegL3ANDHxr7n7T	0.00394800
	2NFAw8krhnZtbvj6kjrXb4mvnHbsrUnwibW	0.00394800
	2NAp8xA5FPqqVZJVwLxDr6KtYZWttC2aw2m	0.00351800
	2N2oocqWaAeCh1qNpv7DcQNnQR2YiDDD8Ye	0.00263280
	2MyonefLASyVbmekMQsQa6BxJSCA7BixxVB	0.00263200
	2Mx9t5YhafjhBgZA8oT6sjNjaKL9F94wLJA	0.00263200
	2NEggTox9NUEgcVeh7HkCf2kdUjH2kAGpB6	0.00251400
	2NE3V6pByqZ5115kpA6EYQ6Erimz19Qmixs	0.00251400
	2NAnmHNLNAzTkC1pCJDPb36h8oegDj7Tytm	0.00251400
	2N5Yna1Pe25B6is3wFnmNfigXSCXaqSwMtB	0.00251400
	2MvJ8YVuddAkXtvydeaqz3AGnBmDi2thWE5	0.00251400
	2NCGwvokZhVAhy76vBquFUMmDqSuUF5gjP6	0.00251160
	2NBi5AyvvrZmoSgAH4oS4uTBdLggg9Mukta	0.00251160
	2MyZvHkRnNxBH42vg9TQUBuF6YB63cnxqQh	0.00251160
	2MwZVhGjYiFpfAcqZfnpY3dJfgcUt7z1ecb	0.00251160
	2NCHknRaka6u2QnhGtQZn2VW3E2MXTZrL2H	0.00209500
	2NCfFHJCbaFSkqFVC2sncT3yLqr7rPiMn1h	0.00209500
	2NCoFoBnNx2h8QE8hxB1aSrv4MNHxqUNGby	0.00209300
	2NCj8b2ZMnurcv9n5WVtoBkNkThmhkNXyvh	0.00209300
	2NCiXD7qHgsy8WPPY4B8wYpZhjcP4Y5xYbu	0.00209300
	2NBnZ1sMWqwzwYActS4Ms2ytzqEQnqkH6z3	0.00209300
	2NA33FwHDyMxQtYs29VypiTbqwBbh61n2DX	0.00209300
	2N1vFwm5X26SGFAWc15c3TrhZvUXo8NwDJs	0.00209300
	2N1jekFARn6kMaPn9iXdpaNNUwNBfbir8CB	0.00209300
	2NFHTZX3RNaNJB1M3oeKJfDqBmrm2T9qrYH	0.00148200
	2NFDPToPWgkwNSc9kWKb9gHpzP7pJt3SEsc	0.00148200
	2NE9GVq1dKqo74r1x21HVmktiUMtimYFfyG	0.00148200
	2NE3ccnGC9LcnaXgLyUYs6mJNsytyjbhtp4	0.00148200
	2NAd7cWwAYdrh9U6NoossPe9pLRGbtuJ9rh	0.00148200
	2MtMQ2zgzBh98Xbsvc9rFDkdFzxtTjBrYjH	0.00148200
	2N9VtUWgHPpi17ccqcoKPXDpE5twHHN228W	0.00101760
Показать больше +21

37 выходов [ потрачено]	0.07063470tBTC

2MxRGt6Q7E1U61tAzwLh7XjXdwbB7WtKHs8	0.00296160
2N1mE9MPaPqc4EGfaAmmBZAFvUhi5TGauxj	0.00100000
2N8Y6jj64d8gyvyZrVsVRJu5uMEQ4eRBwZ6	0.00100000
2MzaGW3YPYd4CiGMoPhFDbMiuCsdViRuEUc	0.00148080
2N2zSsXPSoWM456jBct7gVQVNsCuewcfPMy	0.00061700
2NABxZNW8s3MJQDAYiXYnnvTkYm4YS7D5Nt	0.00123400
2NAXCceu9UNPHM6WzdYCVzJKthBFt6RrnCx	0.00123400
2NCsE3pipFMLnAsEai1NnFaPGpAgPsCSqPR	0.00123400
2NFKqMUcvomFy3CMJKDZCxRQTJ3hMKyJLJG	0.00699450
2NEzTwgxdw3vNrRr2kVNmQmubWq3cVLCZ9S	0.00061700
2NFL2HCKQHWwz9NYTBjHmg1FTCSnFWhVrK6	0.00123400
2MteVE6v7jbbTALpcPfrybGrqy1ysvbAk64	0.01396000
2MsaVuMhEypz3VVmrehgQ32Tf3c9qX48JpL	0.01396000
2Mu6gZjxUFk4ktHta1AoUE5cijpAG7VMbQw	0.00123400
2MuB1kKXv9C7BGuyVFLNXKYkJxPiNcZXXyK	0.00123400
2MvR7q8ADhDCgRFPBTFX3Lo1gMpooErVtiy	0.00123400
2NANRYsvTc2aya9Kge1LnBVhbhRhFBU3GQH	0.00049360
2NCFY9V9YWV7Dpf7FkEwUhPoJzHkJz91wdU	0.00049360
2NCjmLFN86dqV3pcT94E9tueS5ExL7ELG3F	0.00049360
[19] 2NFLF3cmTaNzTBnxVtT8Aj9L3wiLuMLE5rg	0.00040000
2NFLG7yF3aGm3GBoVHAzNC4Z4duPfUbQVcJ	0.00080000
2NFM6Ar1WLG2fmA3VcWd53mwQK4PsRRN3ki	0.00098720
2NFLuYmfyLjoQ8jGnunHezMwtG6sqgCfvdf	0.00098720
2NFmfdB1MQXtcjPYmJDrjAzM6Zj92bkmRXj	0.00050000
2NFmUrVoa2gF6AVnrra2yhxVEzt7LpyBtQm	0.00061700
2NFnafaxmU9Eo35uRn3D1RjUeJvNBrXUUf8	0.00049360
2NFNZHi7d7SzHhSgsSrwjn3pXi9KHtaZxNE	0.00098720
2MsNrxcB4VzyxEj5ygybtugJBJ5QAc95dok	0.00098720
2Mt7pWrFhj7EyNJSSxdgUMAoRf7yZGAFwYE	0.00080000
2MzWu9Aubj21tPHPkyUivaBEGRU4oWoeW3x	0.00074040
2N1PZ5wnK7Pihw5eKi6THVVmjfMk72GfPsV	0.00074040
2N2KFdRE9VmN9hmFZHDgE5v1WR7gSefrwVh	0.00148080
2N2vqxWmXZ4s1qntowKhJ1FKCSPkb29VxRq	0.00148080
2N3GgCiCaiofkMXUMQF1DaEcuEGB4LiEnJo	0.00148080
2N3ozkAeHoLJ12JMbNjhaXzo3cFTSKg1hjs	0.00148080
2N45HtP55JSw9GayZ1qYGKXfzetQ3KJHT28	0.00148080
2N4C1LfBJaGrgb1HPXVZeFe9qEpDoEBh6kS	0.00148080
Показать больше +27

Комиссия:	0.00004310tBTC
Сумма:	0.07063470tBTC

Скрипты входов

0 P2SH 2NFhFQgR1tgb2iFwHHrFiegL3ANDHxr7n7T

SigScript	OP_PUSHBYTES[22] 00147b27fb8b4879e0fdde4adda04b3d21c93ab537e4
Witness	304402206dccf42890b9e9dcd25329862f3911355c12dcb702c233f4c2123d120676474102204f2ba68bb019ea96f8f8e2affa4fe9135a6d5f1ac76fdc437c84781e23e05f7101 03ff620e07f274d789cb5090e98c1295e7f37d8f8775a69766664051a1782e3172

1 P2SH 2NFAw8krhnZtbvj6kjrXb4mvnHbsrUnwibW

SigScript	OP_PUSHBYTES[22] 0014d8caf2263c50652341836516a660fd585c99adb1
Witness	30440220616574949fd3ee245d662e06d6505c63b3aded01cadc705f09fa389924362abd02203b6cbbe6700e73b49735af682253df1a3142100d373d740bbf5601ec9b2e3a5601 03db811302de4b3feb35e684e76bfd19be9cdadaf7b165eb36b2dfe2e8cfc75e06

2 P2SH 2NAp8xA5FPqqVZJVwLxDr6KtYZWttC2aw2m

SigScript	OP_PUSHBYTES[22] 00149a9078e8b246aa2362f48b1d15e310c7c8bc609d
Witness	3044022040edeff86aaaea56ed8014001a724ffe400511f158e360e8f013cdf71cd2ec6c02204a390645fc96489225190b02159db3babeb74da2b666fa1b7b5217f459ed804201 03dde5d40c2cfcea568298a2a5a9d70d1ffd46bebd29ad0b06a1bee3921bae7cc4

3 P2SH 2N2oocqWaAeCh1qNpv7DcQNnQR2YiDDD8Ye

SigScript	OP_PUSHBYTES[22] 00143888b017ce6159b636129cbd125617b551b75c8d
Witness	304402203be8a76753366479870cfa323a875521f960174c14a0585f4c630aa85e84c67c0220155a3e337b3a98e5bdc5987c934ed172b655cf5a4af0d4bd32d1493fc69b0c2d01 030bc3b852f4c1edfef12321936a42f1f4dd9eaef2dcb1e8e23b4c18ba47084aca

4 P2SH 2MyonefLASyVbmekMQsQa6BxJSCA7BixxVB

SigScript	OP_PUSHBYTES[22] 00149eaff49945d89a5335ba64c13945b95898b79280
Witness	304402200f43e2c9fb07c79d05b918bf27f70b0ddbb82ee435c5e867cb310b36197fb13a02204ed8fbf27b8e574e02c39d7527c134ca4b0fffb5a9192a1a79592820a0663cf101 02fda834d142aa296503814a82b878570714d4dd30057bda5c72aa7f279f4b81df

5 P2SH 2Mx9t5YhafjhBgZA8oT6sjNjaKL9F94wLJA

SigScript	OP_PUSHBYTES[22] 00143cdbda532b4f209628d92151708a661d3569a291
Witness	304402201f192fcb72e4448926d0461307dff217472fee8aee1c82fecb7e58890c49ea7202206d38ee1a48a150d7d1dee8871178cc3efdcaee73369ca4fef53bbc3c497ad49201 026c46830c4fead10e4fcc68df17f6211c00ff3b65ae2ba09601786c40690f16dc

6 P2SH 2NEggTox9NUEgcVeh7HkCf2kdUjH2kAGpB6

SigScript	OP_PUSHBYTES[22] 0014d1891991d006be47b310bebb9aa3f5c878d8c0e9
Witness	304402207905fc28abfe950c11ccf897afaf74493868b8e0631868bfea02fd5026cfeb9b022010e4b6fef187e1c37b93ddca30c6d7d1b2c84cb9e5958fd2798d4d58a34cde6201 03c0e0fd259690967048be9e4fdf19e97cd0678d511d3aa77130efa201f6ec6c08

7 P2SH 2NE3V6pByqZ5115kpA6EYQ6Erimz19Qmixs

SigScript	OP_PUSHBYTES[22] 00143088dd0249f84ae45b2c771e8527a2f38cb83fbf
Witness	3044022048da1f0d78f76265cce1a0c7c4e9e6a3f801cc78298309b5924519fc1fc9f79e022028285538fb5eee66af70b3268d13bb58db54c29cfe6b8102901c34ab75902e4701 0225a70e8e3e772c0c3eb0491a6f2d4661a16895d987ea89efcdc9168c173bcbf7

8 P2SH 2NAnmHNLNAzTkC1pCJDPb36h8oegDj7Tytm

SigScript	OP_PUSHBYTES[22] 001496ea63144719a24aa4e609c27c1318fb75729a8d
Witness	30440220491b6b454d83ce6142f566e29f0a18f217cfdc91bf3fee6abe8968c2b6ffaf3802205a94e2d81eef1c32168c1d873f12dd2e5b0993a3cdfea19d21b2b1000f1e3a1a01 024b6c8e446909c4c61672b9d6499debe9362f9f560482b03f575d54ac8ce93998

9 P2SH 2N5Yna1Pe25B6is3wFnmNfigXSCXaqSwMtB

SigScript	OP_PUSHBYTES[22] 0014c4da43c72e45548d4e3e6781b749e4a2af62bbf5
Witness	304402207653530f6b67436335b714a3e77da8b138ec5ed866a7e7a20e071d52004c57630220429fc90aa4339e0205dd3b527a9d6197666700795d46f56fbcea656dca1dd8ea01 03014e20dc66e1dd18022ec26fa5b8848ad1b018e4cbb325367164eac0fc61fa6f

Показать больше +21

Скрипты выходов

0 P2SH OP_HASH160 OP_PUSHBYTES[20] 38bf34270eee2efb73306126042813e67ecc379d OP_EQUAL

1 P2SH OP_HASH160 OP_PUSHBYTES[20] 5d6d9d9a91b29938cf2fcd9c1aa3ff41c75a1f58 OP_EQUAL

2 P2SH OP_HASH160 OP_PUSHBYTES[20] a7bae7c0b7eacebcbea5ab288240c2483ee1d511 OP_EQUAL

3 P2SH OP_HASH160 OP_PUSHBYTES[20] 5062e1b0c1215b8b471bba77054d80677c8151fc OP_EQUAL

4 P2SH OP_HASH160 OP_PUSHBYTES[20] 6ae5c5e239619360df9f648da9e6a659334dbf22 OP_EQUAL

5 P2SH OP_HASH160 OP_PUSHBYTES[20] b9dc02b17b2d82ead2e63cd84fb4777488da33fc OP_EQUAL

6 P2SH OP_HASH160 OP_PUSHBYTES[20] bd7fa5cc85926dcedb5a047fdcc85259cc1a5afc OP_EQUAL

7 P2SH OP_HASH160 OP_PUSHBYTES[20] d7396a5b966ecc85a8e59540846c5415894e3b2d OP_EQUAL

8 P2SH OP_HASH160 OP_PUSHBYTES[20] f231f3e00d1604a655b9445869794ec30097dac6 OP_EQUAL

9 P2SH OP_HASH160 OP_PUSHBYTES[20] ee882d55da824a9ced2f3b612e572e08a67bd2d2 OP_EQUAL

Показать больше +27

Показать скрипты

SigScript	OP_PUSHBYTES[22] 0014787f724b5bf7493f65b2499099933dfdc65346cb
Witness	3044022003e915a13f0f1479e59f9e7253a7787b6b5140c3e307ff91a3046abd03e948a1022052f038403b72a41597d7312cae425590df4b703e4946e6814db3e767c540ddff01 0222f11d167e56700e8b4893ff77e61e270cf7582265e0c019faa5383d956c6af1

SigScript	OP_PUSHBYTES[22] 0014fd96c3fadcce7f135e93d596a729667619e78a4f
Witness	304402201dcd4ef3a3d3ab7aca60fe4a0a8b481ab5c2a106b22c7eeb97e6ff73b44027b5022008ca933eec95bfe9cf30d6d04a81bf8b57bf45b61e02766f23eed85eb223c5ff01 037f3727f6435b985334be9e8f6f6a49d5244ca096aa0b01c5a9dec26a691e456f

SigScript	OP_PUSHBYTES[22] 00140345c1df2a0d2da04a74674d3f7eb22af0e39fc3
Witness	304402205a055146d8c621ef8f159cd67f521a8b3edb2450e2dcf6b936aa773aa7757ca702207d5bdd71687d522dd22d5bff8d9d5485bc1d57b301c47693316ec3db44b8d2cf01 022ef81324fa03584070565f1c28c8dfc640b09dcda5f52ffd7c1ceb06f9a31154

SigScript	OP_PUSHBYTES[22] 00146ba360ffcc5fa7de3e68a434ed0b7eb801fdddab
Witness	304402202f2c183a3a91dc7c91068204812ead646308589b283410ea9671dcbdc8ddffdb02203548dc257ab85ddbb69edaddf7b8ebd86f2ef52886a4f65e2e001201654ed20201 03e236806245c0e7f6e34c8f8330a14dc45d3734024ee24af5adbf9d5379fa6023

SigScript	OP_PUSHBYTES[22] 0014fe6841b3586970826be47f8c52fe811fe715604b
Witness	3044022009cd3dbad1c618c432daa9636e3902775c04d73460cd98596605b8ef7320abad022018efaaacbbc1d8008a25a4d276d8e9795a83a37487db4baa886c3eb02f20834a01 03d251fe7696a01b02dbf157fb152bef3ddb7077aec17556c894b25995bb429097

SigScript	OP_PUSHBYTES[22] 0014e922b30a669ce5ef103a545cf4b6396e57b2b71c
Witness	3044022070b6ceafa2fbee08e989c17a47caa849a6a20ac0d52e5bebea973aff94ba37ca02204baa3b4aa1e63cedc66f3d95b49eb6ba75ddee650da857dccbfec8d4ce02ba4d01 02daa4c6cd042a15f5720aa3b2ab0fb503ec4c5b53f62892f70c16a2d4f4d054d1

SigScript	OP_PUSHBYTES[22] 0014faddcb08b854f36d67463cb887ffaa9dcfa768ce
Witness	304402204413b8531966ca3b8f495c0fdf20bc192086cb765209a1e9126fec2b76f35484022019d8af13a76c83e6b77f4dbecd00c7a1b74b393b7259753e141a920317f7c88901 034af339dd2d7eb96f6219d9cc111977bb82d799d3607e6769f0b04f09d52bc9da

SigScript	OP_PUSHBYTES[22] 0014676748713299982117b359198f991998503b27b5
Witness	304402207fa8c5fc9cd9c49475464d974d8ec15b1f6ecb14da5ce4c744bb667b7e11c07c02204bfea4562c454cb9ab9b09633b0145256386ca671ef5d423fd5edc633763020401 0288d4f50b80c1ea7eb9259a89359084c34fe15c1710f9259e64df1752517b8d4e

SigScript	OP_PUSHBYTES[22] 001454a13d3ec0d2a954e910d80fcc84ee6b8ef289ab
Witness	304402207664655b6d32f8b4db80e1a09fb80672e9be9bc507698ed77e979c0f95eeaadf02202d49dfdc964c2db6fdff98e73cdd04593ed2df212638cef2a206cd4ad2789d9601 03895fec2e48e2c9bc19791ed968fe08e167b721de2bd882eff6352534f59f96b5

SigScript	OP_PUSHBYTES[22] 00147132b8b04a45ea226a661b704c6924546a471d76
Witness	304402207b43fdeb2c08970e14c55ad33754770b9043e454b21cfcf30bbf6ee94c94d86d02206baa06247c9ab56a79c6289caaedd180ddf38d3d40e3da5eb6efd9b737b8fb9e01 03cb1fdc7f7a559e0f260b321359cb118277b36cf0430037bbb943e94b9d4ed09e

SigScript	OP_PUSHBYTES[22] 0014ec034be377b8e39c3255d8f79d9cd94ef8c496e5
Witness	304402203a004a2be93bbbe3bdb50f219ae4e78916fe197dbf4c994f3f9d0e4924c37608022067a81f73d7fb4ae2429987f8d08c176c7e98cff166217cf5941ed9e465a5b6fc01 033d11d9394791e753097449d98463597974182b19e69f71a3a1fe3882b3dfbbb9

SigScript	OP_PUSHBYTES[22] 001481e86bc8daac2fb2f9982f40d57bfe3148b4a9d4
Witness	304402203538555fa94f1110b28d8a3e4b2797936932b917653cea2633075343017b8fdd022046c384e03cec37017ecbfe7312c0c942b8b002963d6f40454c1e6b60e752c0da01 02ef499a2b58837580bb31881ef649787958a7f2303f09a12798b4ff4f4dda03c0

SigScript	OP_PUSHBYTES[22] 0014fa105e447b46a497b12a593c06c97e15a7a6d881
Witness	3044022042f3ab35f15aafecbd7464b514903e1ef311dd7bfa7ed0df4e35b96bef70339d02205460eb6d5d3473821530882d2a0395c929467ce5b7578ad23c978458c45d358d01 03e17da9520db3ef35920c1947f1971838f1eedb8e270892b3082c5fa256256066

SigScript	OP_PUSHBYTES[22] 0014db074b5821893fee3c683dde5b4aa61d94f3e838
Witness	304402207a0118a0cca8f6ab90a602edb059aec8aac237d8cd540f335f16248d741e9d730220376f9914dff6c68ae15bd6aec52cef54bd1ddf9f5aa7ea75501ab99b01dd1fd201 026dc4f3036094fc183273bc44c6c74878111e1f57b1ea0afdcec4f564c9eae77f

SigScript	OP_PUSHBYTES[22] 00145416c37d187a1cd8844095acd7e876c467313c77
Witness	304402202cb1c1ea4c16a4e87230c088dd33afb541b6330a23f47320ab13e95072aa1b1e0220563f445eb7e45abe458c7a89b6c342f0b36f0a303eb45932ab3d6488eb5643de01 03d9d6ea55d6579812da2e14a4571a567e012de112442f7e67722388fb093e1c64

SigScript	OP_PUSHBYTES[22] 00141d62034e04a5fcc0060808d20b7e9baf68e5c8b7
Witness	3044022023fd548b09eb159bc1018f9e03614811db044e5a3be1809b3c305127d5ebf4de0220190a30912abc3dd9c066793077273bc19d6ef7b328a04bd130237a8cd9d3730401 035b13a2c8548c8faf25f6c49bc4de2b0519952497fadeab1d7b2bf23782b5ebeb

SigScript	OP_PUSHBYTES[22] 001487e7d70bdb9106d96c378252bd456454459f1465
Witness	3044022062ec9d9e46357a2a96a8f388535e0eeb677817dfb102e97d669d7d647a7f8a93022073e66b2ca1cf864083a533b82bf5aa974f51652b9f22c8d43faf369081d76e6301 03840f432e46e256c7b9a1dbea5c875ad57962d162146efe179f4dcbe50aad1d04

SigScript	OP_PUSHBYTES[22] 0014e60c68be3591cf9842f92e59a73cc8ec5a381e8c
Witness	3044022008fc3c2e52eccfcf46bb413b48817daa47126501b91fa3480b70d1108b6af6c7022059974782ddb77edb7e20752b5fc7ebd4a717f9d0860e3189c44b4571e638d29b01 02be8632c47b4438ae91c37854b80db53eb3583d329aa4eea51d4195b4c8f80423

SigScript	OP_PUSHBYTES[22] 0014b5facb174a45356a421fd368a2d425a6d197adc2
Witness	3044022033c0217ea565e7dab02a2e776da52f1daa9fdcd6f67b519e7750305fcc6fe38c02207c5f312343dedd404de45664b2beea40c28da439212b2251db12862b1028027801 0336bf90030a7c66eed5a2a03ba961c1300a91b0da256602c4edb63389338029e6

SigScript	OP_PUSHBYTES[22] 001413c50e4ed0d2e19aec0d5b0beb47dc5f75472679
Witness	304402204fbfd1b658bcba14e406a1f41c47cee0582e71816d75314f819a4f12e09d65f202204b8cfd32f28bc4875f6c40e56bb01376d72a2772bfdff8428b3df43badddd03e01 038df1d9763b3d9aadb8e95918054254b9c84c33979be2e058d82bdaea06288224

SigScript	OP_PUSHBYTES[22] 001425af3c4f3a496c46ce0823b024008dd7f742ca93
Witness	30440220431905b7928352942fbd035b7b290c5e6c0ce0ef74050c6769c847c0805e94ea02207164e124684187c5486f8d424994e926fc3fbd8167333bbf8dc73da4c7a52a5001 02ccce82c43f2814a5277430e24b6e4ad85bbcbaa664e6a5bf0b02ba5334136566

3 436 243

3 436 243

7 084

Bitcoin testnet транзакция 9d830dc2708284bec95126db2b3b32252c999fdd92406609d26720fe84699e8b

1f280321ea683ea3bfd8a56795fb0ea2d0c7219b1d14db706378dd67a7e304a4