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

open(my $fh1, ">>", "output1.txt")
    or die "Can't open > output1.txt: $!";

open(my $fh2, ">>", "output2.txt")
	or die "Can't open > output2.txt: $!";

my $count = 1;
while (<>) { # Read all files that provided through ARGV
    chomp;
    if ($count == 1 or $count == 2) {
	say $fh1 $_;
    }
    elsif ($count == 3 or $count == 4) {
	say $fh2 $_;
    }
    if ($count == 4) { $count = 1; next; }
    $count++;
} continue {
    close ARGV if eof; # reset $. each file
}

close($fh1)
    or warn "Can't close output1.txt: $!";

close($fh2)
    or warn "Can't close output2.txt: $!";