#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double pi=3.141592653589793;
typedef unsigned long long ull;
typedef long double ldouble;
const ll INF=1e18;
#define rep(i, n) for(ll i = 0; i < (ll)(n); i++)
#define rep2(i, s, n) for (ll i = (s); i < (ll)(n); i++)
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


int main(){
    // 小数点以下第15桁まで表示させる
    cout.precision(15);
    cout << fixed;
    vector<int> p(3);
    int count = 0;
    ldouble ans;
    rep(i, 3) {
        cin >> p[i];
        if(p[i] == 0) count++;
    }
    sort(p.begin(), p.end());
    if(count == 0) {
        ans = (ldouble)(p[1] + p[2]) / (ldouble) (p[0] + p[1] + p[2]);
    }
    else if(count == 1) {
        ans = (ldouble)p[1] / (ldouble) (p[0] + p[1] + p[2]) / (ldouble)2 + (ldouble)p[2] / (ldouble) (p[0] + p[1] + p[2]);
    }
    else if(count == 2) {
        ans = (ldouble) 1;
    }
    cout << ans << endl;
}