#!/usr/bin/perl -w
use strict;
my %d = map{
        /^(\w+) /; 
        $1, $_;
    }grep{
        chomp;
        /^\w+ \d+/;
    }map{
        local @ARGV = ($_);
        <>;
    }<F*.dat>;
open(MRG, ">merge.dat") or die "Oops! There was a problem: $!";
print MRG, $d{$_}."\n" for(sort keys %d);
close MRG;