#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;
    assert(0<=P && P<=100);
    assert(0<=Q && Q<=100);
    assert(0<=R && R<=100);
    assert(P+Q+R>0);
    double val = 0;
    val = max(val,(double) P+Q);
    val = max(val,(double) Q+R);
    //val = max(val,(double) R+P);
    cout << fixed << setprecision(10) << val/(P+Q+R) << "\n";
}