#!/usr/bin/perl

use strict;

open(FILE, "<f.txt");
open(OUT, ">out.txt");
while(<FILE>) {
    chomp $_;
    if( 1 .. 4 ) {
        print OUT "$_\n";
        next;
    }

    for( my $i = 0; $i < length($_); $i++ ) {
        if( substr($_, $i, 1) =~ m/(\^|\#)/ ) {
            substr($_, $i, 1) = "$1";
        } elsif( substr($_, $i, 1) =~ m/(.)/ ) {
            substr($_, $i, 1) = "$1$1";
            $i++;
        }
    }
    print OUT "$_\n";
}
close(FILE);
close(OUT);