use proconio::input;

fn main() {
    input! {
        (a, b, c): (f64, f64, f64),
    }

    let cos = (a.powi(2) + c.powi(2) - b.powi(2)) / (2.0 * a * c);
    let sin = (1.0 - cos.powi(2)).sqrt();
    let s = a * c * sin / 2.0;
    let r = (2.0 * s) / (a + b + c);
    println!("{}", r);
}