#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
using ll = long long;
const ll MOD = 998244353;


int main() {
    double a, b, c;
    cin >> a >> b >> c;
    double x = (a + b + c) / 2;
    double s = sqrt(x * (x - a) * (x - b) * (x - c));
    double r = s / x;
    cout << r << endl;

}