#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>

using namespace std;
typedef long long ll;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    double p, q, r; cin >> p >> q >> r;
    double sum = p+q+r;
    p /= sum;
    q /= sum;
    r /= sum;
    double ans = 0;
    ans = max({max(p, q+r),max(q, p+r),max(r, q+p)});
    cout << ans << endl;
}