fn main() {
    let mut xx = String::new();
    std::io::stdin().read_line(&mut xx).ok();
    let xx: Vec<&str> = xx.split_whitespace().collect();
    let mut ff: Vec<f64> = xx.clone().into_iter().flat_map(str::parse).collect();

    if xx[0] == xx[1] {
        println!("{}", ff[0].hypot(ff[0]));
    } else {
        ff.sort_unstable_by(f64::total_cmp);
        println!("{}", (ff[1].powi(2) - ff[0].powi(2)).sqrt());
    }
}