#!/usr/bin/perl

my %sizes = qw( a 1 b 2 c 3 d 3 e 2 f 2);
my %times_seen;

for my $v (values %sizes){
    $times_seen{$v} ? $times_seen{$v}++ : ($times_seen{$v} = 1);
}
for my $k (keys %sizes){
    if($times_seen{$sizes{$k}} > 1 ){
        print "$k => $times_seen{$sizes{$k}}\n";
    }
}