pub struct Gen {
    state: i64,
}


pub fn new(seed: i64) -> Gen {
    Gen{
        state: seed,
    }
}

impl Gen {
    pub fn rand(&mut self, max: i32) -> i32 {
        self.state = self.state.wrapping_mul(6364136223846793005).wrapping_add(1);
        (self.state >> 33 & 0x7fffffff) as i32 % max
    }
}