#!/usr/bin/perl

# http://perlmonks.org/?node_id=1146923

use strict;
use warnings;

$_ = join "\t", qw(1 A 1 B 2 G 2 H 2 V);

1 while s/\b((\d+)\s\S+)(.*?)\s\2\s(\S+)/$1:$4$3/;

print "$_\n";