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Regular Expression
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^\d*\K(\d)[a-z](?>\d*[a-z]+)*\1
/
gm
Input 1
1
New
8659143296aconite931031567290592196372720165714862606068549452875678894011583394 429537968991065280440972955773783975aconite405304426503915937177910674938356s995 165730080656179172282158326723459395151887a197343544312497429322conitic971943257 242700348160683825750220278124532230615414861aconi0423t2209041629um7534201414279 8095795129421424035773aconit51122048059352421754855393594um083s57745637407177073 203520740229811376acor4730n05675830009456231936341628077162200687753246324478764 0047610666820884722216474722512324028387365649588049630aco5307rns847715766988588 568901339322354170088854729578680996027154709227496061907093046a199546373coustic 293915167531ac31069383748462343642622383007520ou280685412598707stical13002190096 83982473352438654261757963864323333acou021534520556605043806stical2223ly16922171 02309730655acousti3490661184937075557973850179cia014890505513865828185722n085724 26480962052acousti87311144532313023833020698187076874569358847788485c8205ians518 24711482467426173614aco00496247639921262483584020ustic92007815150348941694311s08 1234b4 3c3