fn guess_number() {
    println "Welcome to the Number Guessing Game!";
    println "I'm thinking of a number between 1 and 100.";
    let secret_number = random_number();
    let attempts = 0;

    while (true) {
        println "Take a guess: ";
        let inp = input();
        let guess = to_int(inp);
        attempts = attempts + 1;

        if (guess < secret_number) {
            println "Too low! Try again.";
        } else if (guess > secret_number) {
            println "Too high! Try again.";
        } else {
            print"Congratulations! You've guessed the number in ";
            print attempts;
            print " attempts!";
            return;
        }

    }
}

guess_number();