#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll a, b, c;
    cin >> a >> b >> c;
    double s = (a + b + c) / 2.0;
    double r = sqrtl((s - a) * (s - b) * (s - c) / s);
    cout << fixed << setprecision(15) << r << '\n';
}