#!/usr/local/bin/perl
unless (open (INFILE1, "merge1.txt")){
	print ("cannot open input file merge1.txt\n",'press ENTER to EXIT');
	$in = <STDIN>;
	die ("Cannot open input file merge1.txt\n");
}
unless (open (INFILE2, "merge2.txt")) {
	print ("cannot open input file merge2.txt\n",'press ENTER to EXIT');
	$in = <STDIN>;
	die ("Cannot open input file merge2.txt\n");
}
$line1 = <INFILE1>;
$line2 = <INFILE2>;
while ($line1 ne "" || $line2 ne "") {
	if ($line1 ne "") {
		print ($line1);
		$line1 = <INFILE1>;
	}
	if ($line2 ne "") {
		print ($line2);
		$line2 = <INFILE2>;
	}
}
print ('press ENTER to EXIT');
$in = <STDIN>;