my %edgeHash;
my %countHash;
while(<stdin>){

	# Reading an edge list
	if(/^\s*([0-9]+)\s+([0-9]+)\S*$/){
		my $a = "$1";
		my $b = "$2";
		my $good = "1";

		# Eliminate loops
		foreach my $item (keys %edgeHash){
			foreach my $item2(@{$edgeHash{$item}}){
				if($item2 eq $b){
					$good = "0";
				}
			}
		}

		# Add items to the edge hash
		if($good eq "1"){
			if(exists($edgeHash{$a})){
				push @{$edgeHash{$a}}, $b;
			}else{
				push @{$edgeHash{$a}}, $b;
			}
		}
	}
}