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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ld A, B, C;
    cin >> A >> B >> C;

    ld s = (A + B + C) / 2.0L;
    ld S = sqrtl(s * (s - A) * (s - B) * (s - C));
    ld r = S / s;

    cout << fixed << setprecision(10) << r << "\n";
    return 0;
}