class Random {
    field int a,b,c,m;

    constructor Random new() {
        let a = 123;
        let b = Keyboard.readInt("Please input a random seed.");
        let c = 456;
        let m = 789;
        return this;
    }

    /** Deallocates the object's memory. */
    method void dispose() {
        do Memory.deAlloc(this);
        return;
    }

    method int random(int n) {
        let b = mod(a * b + c, m);
        return mod(b, n);
    }

    method int mod(int a, int b) {
        var int d, i;
        let d = Math.divide(a,b);
        let i = Math.multiply(d,b);
        return a - i;
    }
}