#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;

int main() {
    vector<double> p(3);
    double sum = 0;
    rep(i, 3) {
        cin >> p[i];
        sum += p[i];
    }
    sort(p.begin(), p.end());

    cout << setprecision(10) << (p[1] + p[2]) / sum << endl;

    return 0;
}