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pub fn sqrt(y: u128) -> u128 {
    if y > 3u128 {
        let mut z = y;
        let mut x: u128 = y / 2 + 1;
        while x < z {
            z = x;
            x = (y / x + x) / 2;
        }
        z
    } else if y != 0 {
        let z = 1;
        z
    } else {
        y
    }
}

pub fn min(x: u128, y: u128) -> u128 {
    let z = match x < y {
        true => x,
        _ => y,
    };
    z
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn sqrt_works() {
        assert_eq!(2, sqrt(4));
    }

    #[test]
    fn min_works() {
        assert_eq!(1, min(1, 3));
    }
}