#!/usr/bin/perl -w
use strict;

my %somehash;
my $file = 'data.txt';

open FILE "<$file" or die "Can't open $file for reading: $!";
while (<FILE>) {
    if (/^(\d+)\s+[^\s]+\s+[^\s]+\s+([a-zA-Z]+)$/ {
        $somehash{$2} = $1;
    }
}