Please switch to a 2-dimensional array. See References Quick Reference for the very short story on how to dereference complex data structure references in Perl.

#!/usr/bin/perl -w

use strict;

my ($i, $j);
my @a= (
   [1,2,3,4,5],
   [2,1,3,5,4],
   [3,4,5,1,2],
   [4,2,3,5,1],
   [5,4,3,2,1],
);

for $i(1..4){
    for $j($i+1..5){
        if ($a[$i][0] == $a[$j][0]){
            print "Matched one!\n";
            unshift @{$a[$i]}, pop @{$a[$j]};
            push @{$a[$j]}, pop @{$a[$i]};
            last;
        }
    }
}
[download]

        - tye (but my friends call me "Tye")