use strict; use warnings; my @alphas = split ' ', 'A G C T G G G G A C T T T A G C'; my @nums = split ' ', '34 23 43 45 34 43 45 7 45 43 12 34 32 56 43 67'; my @keep = grep { $_ < 1 || $nums[$_] >= 10 || $alphas[$_-1] ne $alphas[$_-0] } 0..$#nums; print( join( ' ', @alphas[ @keep ] ), "\n" ); print( join( ' ', @nums [ @keep ] ), "\n" );