use Data::Dump "pp";
my %count;
 
 
while(<DATA>) {
  chomp;
  @keys= sort split;
  for my $a (0..$#keys){
    for my $b ($a+1.. $#keys) {
#     pp [$keys[$a],$keys[$b]];
      $count{$keys[$a],$keys[$b]}++
    }
  }
  
}
 
pp \%count;
 
__DATA__
tomD gly4 phil
aesG tomD gly4 phil
aesG phil
aesG tomD gly4