#include <iomanip>
#include <iostream>
#include <algorithm>
using namespace std;
int main() {
    double p, q, r; cin >> p >> q >> r;
    double d = p + q + r;
    cout << setprecision(12) << max({p / d, q / d, r / d, 1 - p / d, 1 - q / d, 1 - r /d}) << endl;
}