#!/usr/bin/env perl -l

use strict;
use warnings;
no warnings 'uninitialized';

my @key_value_pairs;

# Capture key-value pairs from original query strings
while (<DATA>) {
    chomp;
    push @key_value_pairs, { map { (split /=/)[0,1] } split /&/ };
}

# Remove common key-value pairs
KEY: for my $key (keys %{$key_value_pairs[0]}) {
    for my $i (1 .. $#key_value_pairs) {
        next KEY unless $key_value_pairs[0]{$key} eq $key_value_pairs[$i]{$key};
    }
    delete $key_value_pairs[$_]{$key} for 0 .. $#key_value_pairs;
}

# Recreate query strings without common key-value pairs
for my $kvp (@key_value_pairs) {
    print join '&', map { join '=', $_, $kvp->{$_} } sort keys %$kvp;
}

__DATA__
a=1&b=1&c=1&d=2&e=&f=3
a=1&b=2&c=3&d=2&e=&f=4
a=1&b=2&c=5&d=1&e=&f=5

##</code><code>##

b=1&c=1&d=2&f=3
b=2&c=3&d=2&f=4
b=2&c=5&d=1&f=5