use strict;
use warnings;

my (%ops, $first, $second, $op, $f);

%ops = (
    '+' => { 'label' => 'Sum', 'op' => sub { return $_[0] + $_[1]; } },
    '-' => { 'label' => 'Difference', 'op' => sub { return $_[0] - $_[1]; } },
    '*' => { 'label' => 'Product', 'op' => sub { return $_[0] * $_[1]; } },
    '/' => { 'label' => 'Quotient', 'op' => sub { return $_[0] / $_[1]; } }
);
$ops{'M'} = { 'label' => 'Multiplication', 'table' => 1, 'op' => $ops{'*'}{'op'} };

sub getval {
    chomp($_ = <STDIN>);
    ($_) = m/($_[0])/ if $_[0];
    return $_;
}

while (1) {
    print "Enter the first number: ";
    last if !($first = getval('\d+'));
    print "Enter the second number: ";
    last if !($second = getval('\d+'));
    print <<TEXT;

Please enter the operation that you want to perform:
  + - * /
  M = Mulitiplication Table
TEXT
    last if !$ops{$op = getval()};
    print "\n";
    if (!$ops{$op}{'table'}) {
        print "$ops{$op}{'label'} of $first $op $second is ",
               $ops{$op}{'op'}->($first, $second);
    }
    else {
        print '  ', join ' ', 1..$second;
        for $f (1..$first) {
            print "\n";
            print join ' ', $f, map { $ops{$op}{'op'}->($f, $_) } 1..$second;
        }
    }
    print "\n\n";
}