//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define all(a) (a).begin(), (a).end()
using ll = long long;
const ll INF32 = 2e9;
const ll INF64 = 4e18;

void printYN(bool ok){
    if(ok)cout << "Yes" << endl;
    else cout << "No" << endl;
    return;
}

int main() {
    long double A, B, C;
    cin >> A >> B >> C;
    long double s = (A+B+C)/2;
    long double S = sqrt(s*(s-A)*(s-B)*(s-C));
    long double ans = S/s;
    cout << fixed << setprecision(12) << ans << endl;
    return 0;
}