#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using namespace std;

int main()
{
    double p, q, r, t;
    cin >> p >> q >> r;
    t = p + q + r;
    p = p/t, q = q/t, r = r/t;
    cout << fixed << setprecision(9);
    if (p == 1 || q == 1 || r == 1) cout << 1 << endl;
    else if (p == 0 || q == 0 || r == 0) cout << 1 << endl;
    else cout << 1 - min({p, q, r}) << endl;
}