#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=144494;
ll mod=1000000007;
int main(){
    ld p,q,r;
    cin >> p >> q >> r;
    vector<ld>x;
    x={p,q,r};
    sort(x.begin(),x.end());
    ld sum=p+q+r;
    ld s=x[1]+x[2];
    cout << setprecision(100) << (s/sum) << endl;
}