#!/usr/bin/perl
print "===================================\n";
print "= 1.txt + 2.txt > 3.txt           =\n";
print "===================================\n";
open(F, '1.txt'); 
while (defined($a=<F>))
{ 
chomp($a); 
$k{$a}=1; 
} 
close F; 

open(F, '2.txt'); 
while (defined($a=<F>))
{ 
chomp($a); 
$k{$a}=2; 
} 
close F; 

open(F, '>3.txt'); 
foreach (sort keys(%k))
{ 
print F $_,"\n"; 
} 
close F;