#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

int main() {
  vector<int> v(3);
  cin >> v[0] >> v[1] >> v[2];

  sort(v.begin(), v.end());

  cout << fixed << setprecision(10) << (double)max(v[2], v[0] + v[1]) / (double)(v[0] + v[1] + v[2]) << endl;



}