#include<iostream>
#include<iomanip>
using namespace std;

int main(){
    double d[3], sum = 0;
    for(int i = 0; i < 3; i++)  cin >> d[i], sum += d[i];
    for(int i = 0; i < 3; i++)  d[i] /= sum;
    double ret = 0;
    for(int mark = 0; mark < 3; mark++){
        double st = 0, ch = 0;
        for(int dia = 0; dia < 3; dia++){
            if(mark==dia){
                st += d[dia];
            }else{
                ch += d[dia];
            }
        }
        ret = max(ret, st);
        ret = max(ret, ch);
    }
    cout << fixed << setprecision(12) << ret << endl;
    return 0;
}