#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vec<T>>;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int P,Q,R;
    cin >> P >> Q >> R;
    cout << fixed << setprecision(10) << 1.0-1.0*min({P,Q,R})/(P+Q+R) << "\n";
}