#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <optional>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

int main() {
    double min_x = numeric_limits<double>::max(), sum = 0;
    for (auto i = 0; i < 3; ++i) {
        double x;
        cin >> x;
        sum += x;
        min_x = min(min_x, x);
    }
    printf("%.12f\n", (sum - min_x) / sum);
    return 0;
}