#! perl -slw
use strict;
use vars qw[ $a $b ];
use List::Util qw[ reduce ];

my $op = shift @ARGV;

my @hasharray;

for ( 2 .. @ARGV ) {
	for my $indices ( Cnr( $_, 0..$#ARGV ) ) {
		push @hasharray, {
			LIST=> [ @$indices ],
			VALUE=> reduce{
				my $val = eval "$a $op $b";
			} @ARGV[ @$indices ]
		};
	}
}

print "@{ $_->{LIST} } : $_->{VALUE}"  for @hasharray;

exit;

sub Cnr{
	my( $n, @r ) = shift;
	return [] unless $n--;
	for my $x ( 0 .. ($#_ - $n) ) {
		push @r, map{ [ $_[$x], @$_ ] } Cnr( $n, @_[ ($x+1) .. $#_ ] ) ;
	}
	return @r;
}