fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.split_ascii_whitespace();

    let r: f64 = stdin.next().unwrap().parse().unwrap();
    let d: f64 = stdin.next().unwrap().parse().unwrap();

    println!("{:>.07}", output(solve(r, d)));
}

fn solve(r: f64, d: f64) -> f64 {
    (d.powi(2) - r.powi(2)).sqrt()
}

fn output(ans: f64) -> f64 {
    ans
}