use strict;
use warnings;

my $start = 'CTGCCACCGCTGT';
my $end   = 'ACCGCTGTGTTTCGGCCGGCGA';

my $pos = 0;
$pos++ while (!(substr($start, $pos, (length $start) - $pos) 
         eq substr($end, 0, (length $start) - $pos))); 

print substr($start, $pos, (length $start) - $pos), ' ', $pos+1, "\n";