use strict;
use warnings;

my $in = $ARGV[0];
my $p  = $ARGV[1];
my $s  = $ARGV[2];

open IN   , "<$in" or die $!;
open P_OUT, ">$p" or die $!; 
open S_OUT, ">$s" or die $!;

while (<IN>) {
    if (/^>/) {
        if (/pair:/) {
            select P_OUT;
        }
        else{
            select S_OUT;
        }
    }
    print;
}

close(IN);
close(P_OUT);
close(S_OUT);