fn main() {
    let mut rd = String::new();
    std::io::stdin().read_line(&mut rd).ok();
    let rd: Vec<f64> = rd.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let r = rd[0];
    let d = rd[1];

    println!("{}", (d*d - r*r).powf(0.5));
}