#include <bits/stdc++.h>
using namespace std;
int main(){
  cout << fixed << setprecision(10);
  double P, Q, R;
  cin >> P >> Q >> R;
  double p = P / (P + Q + R);
  double q = Q / (P + Q + R);
  double r = R / (P + Q + R);
  double ans = max({1 - p, 1 - q, 1 - r});
  cout << ans << endl;
}