#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (long long i = 0; i < (n); ++i)
using ll = long long;
using P = pair<ll,ll>;
using vec = vector<ll>;
using vecp = vector<P>;
using mat = vector<vec>;
using matp = vector<vecp>;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define all(v) v.begin(), v.end()

int main(){
  double P,Q,R;
  cin >> P >> Q >> R;
  if(P<Q) swap(P,Q);
  if(Q<R) swap(Q,R);
  cout << fixed << setprecision(15) << (P+Q)/(P+Q+R) << endl;
    
}