use warnings;
use strict;

my @p = qw[PA5098  PA5100  PA5092  PA3175];

for my $i ( 0 .. $#p ) {
    last if $i == $#p;
    for my $j ( 0 .. $#p ) {
        print join( " " => ( $p[$i], $p[$j], $j - $i ) ), $/ unless $i >= $j;
    }
}

##</code><code>##

PA5098 PA5100 1
PA5098 PA5092 2
PA5098 PA3175 3
PA5100 PA5092 1
PA5100 PA3175 2
PA5092 PA3175 1