#!/usr/bin/env perl 

use strict;
use warnings;


while (1) {
    my @operands = (int(rand(100)), int(rand(100)));
    ask ($operands[0] > $operands[1], @operands);
}

sub ask {
    my ($subtract, @args) = @_;
    my $input;

    my $answer = $subtract ? $args[0] - $args[1] : $args[0] + $args[1];
    my $oper   = $subtract ? '-' : '+';

    until (defined $input && $input == $answer) {
        print "Nope, try again\n" if defined $input;
        print "What is $args[0] $oper $args[1] ? ";
        chomp( $input = <STDIN> );
    };
    print "Success!\n";
}