#!/usr/bin/perl -w
$a1 = 1;
$a2 = 2;
$a3 = 3;
$b1 = 4;
$b2 = 5;
$b3 = 6;
$c1 = 7;
$c2 = 8;
$c3 = 9;
%squares = ("a1", $a1, "a2", $a2, "a3", $a3, "b1", $b1, "b2", $b2, "b3", $b3, "c1", $c1, "c2", $c2, "c3", $c3);
print "Remove which one? ";
chomp ($response = <STDIN>);
make_blank();
print values %squares;
print "\n";
print %squares;

# makes the moved piece blank
sub make_blank() {
  foreach $key (keys %squares) {
    ($squares{$key} .= "") if ($key eq $response);
  }
}