#!usr/bin/perl-w $a="ATCGGCGCCTAT"; code?? print" Letters at 1st position:\n A1=$A1; T1=$T1; G1=$G1; C1=$C1; \n Letters at 2nd position:\n A2=$A2; T2=$T2; G2=$G2; C2=$C2; \n Letters at 3rd position:\n A3=$A3; T3=$T3; G3=$G3; C3=$C3; \n"; exit;