#!/usr/bin/env perl

use strict;
use warnings;
use autodie;

while (<STDIN>) {
    print;
    /^B (\S+)/ && read_input($1);
}

sub read_input {
    my ($file) = @_;

    open my $fh, '<', $file;

    while (<$fh>) {
        print;
        /^B (\S+)/ && read_input($1);
    }

    close $fh;

    return;
}

##</code><code>##

m
m
n
n
o
o
B pm_1081744_tst.bat
B pm_1081744_tst.bat
a
b
c
B pm_1081744_tst2.bat
z
y
x
w
1
2
3
p
p
q
q
r
r