#!/usr/bin/perl
#use strict;
#use warnings;

open fh1,"<C:/Perl-Script/file1.txt";
open fh2,"<C:/Perl-Script/file2.txt";
open fh3,">>C:/Perl-Script/file3.txt";
@a=<fh1>; 
@b=<fh2>;

foreach $b(@b) {
	@k = split ' ', $b;
	$hash2{$k[0]} = $k[1];
}

foreach $a(@a) {
	@k = split ' ', $a;
	$hash1{$k[0]} = $k[1];
}

while(($k,$v)= each %hash1)
{$hash1{$k} = $hash2{$k} if (exists $hash2{$k})};

foreach $value (@a) {
	print fh1 $value;

}