C:\>ftype /?

    ASSOC .pl=PerlScript
    FTYPE PerlScript=perl.exe %1 %*

would allow you to invoke a Perl script as follows:

    script.pl 1 2 3

If you want to eliminate the need to type the extensions, then do the following:

    set PATHEXT=.pl;%PATHEXT%

and the script could be invoked as follows:

    script 1 2 3

##</code><code>##

#!/your/perl/here

use strict;
use warnings;

my @precio;

open PR,'medicines.txt';
@precio=<PR>;
close PR;
chomp(@precio);

print("\n** MEDICINE PRICES BY DOSES PER MONTH **\n\n");

my $acumes;

foreach my $li (@precio)
{
	next if ($li=~/^[_#\W]/);
	my ($med,$uni,$pre)=split(/\t/,$li);
	my $dos;
	print('Daily dose of ',$med,'? =>');
	$dos=<>;
	$dos=~s/[^\d\.]//g;
	my $tot=sprintf("%6.2f",$pre/$uni*$dos*31);
	print('  Costs.................'," \t\t\t$tot \$\/month.\n");
	$acumes+=$tot;
}

my $lit="\nTotal to spend with medicines every month:      $acumes \$\n";
print('=' x length($lit),$lit, '=' x length($lit),"\n");


##</code><code>##

#!/your/perl/here

use strict;
use warnings;

while (<>)
{ 
	print "one: $_";
}

print "\n\n: now reading from STDIN: \n\n";

print "Enter data: ";
while (<>)
{ 
	print "two: $_";
	print "Enter data: ";
}