2.pl

#!/usr/bin/perl
use strict;
use warnings;
while (<>) {
  my ($x, $y) = split;
  my @xs = `perl ./1.pl $x`;
  map chomp, @xs;
  my @ys = `perl ./1.pl $y`;
  map chomp, @ys;
  while (@xs || @ys) {
    print shift @xs if @xs;
    print "\t";
    print shift @ys if @ys;
    print "\n";
  }
}