while( <> ) {
    chomp;
    my( $key, $subkey ) = split;
    $h{$key}{$subkey}++;
}

##</code><code>##

#! /usr/bin/perl -w

use strict;

my %h;

# two different subkeys
$h{foo}{bar}++;
$h{foo}{rat}++;

# one subkey
$h{fob}{rat}++;

# one subkey seen more than once
$h{fod}{car}++;
$h{fod}{car}++;

for my $c( keys %h ) {
    if( scalar keys %{$h{$c}} == 1 and $h{$c}{(keys %{$h{$c}})[0]} == 1 ) {
        print "$c has a ${\(keys %{$h{$c}})[0]}\n";
    }
    else {
        print "$c is complicated\n";               
    }
}