#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

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

    int p, q, r;
    cin >> p >> q >> r;

    int sum = p + q + r;
    cout << fixed << setprecision(15) << 1 - min({(double)p / sum, (double)q / sum, (double)r / sum}) << newl;

    return 0;
}