fn chowla(n: u32) -> u32 {
    var sum: u32 = 0
    var d: u32 = 2
    while d < n {
        if n % d == 0 {
            sum = sum + d
        }
        d = d + 1
    }
    return sum
}

pub fn main(world: World) -> Void raises {
    if chowla(12) == 15 {
        check world.out.write("chowla ok\n")
    }
}