#!/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;
    }
}

##</code><code>##

/^            # Anchor to beginning of string
  (           # Capture to $1
    \d+       #     one or more digits
  )           # 
  \s+         # One or more whitespace
  [^\s]+      # One or more non-whitespace
  \s+         # One or more whitespace
  [^\s]+      # One or more non-whitespace
  \s+         # One or more whitespace
  (           # Capture to $2
    [a-zA-Z]+ #     One or more letters
  )           #
$/x;          # Anchor to end of string

##</code><code>##

while (<FILE>) {
    chomp;
    my ($value, $key) = (split /\s/, $_)[0,3];
    $somehash{$key}   = $value;
}