while (my $line = <IN>) {
    chomp $line;
    ...

##</code><code>##

use strict;
use warnings;

for ('A' .. 'C')
{
    print "Outer: \$_ = $_\n";

    for (10 .. 12)
    {
        print "    Inner: \$_ = $_\n";
    }

    print "Outer: \$_ = $_\n";
}

##</code><code>##

23:21 >perl 2004_SoPW.pl
Outer: $_ = A
    Inner: $_ = 10
    Inner: $_ = 11
    Inner: $_ = 12
Outer: $_ = A
Outer: $_ = B
    Inner: $_ = 10
    Inner: $_ = 11
    Inner: $_ = 12
Outer: $_ = B
Outer: $_ = C
    Inner: $_ = 10
    Inner: $_ = 11
    Inner: $_ = 12
Outer: $_ = C

23:22 >