fn main() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let p: usize = itr.next().unwrap().parse().unwrap();
    let q: usize = itr.next().unwrap().parse().unwrap();
    let r: usize = itr.next().unwrap().parse().unwrap();

    let m = std::cmp::min(p, std::cmp::min(q, r)) as f64;
    let s = (p + q + r) as f64;

    println!("{}", 1. - m / s);
}