#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define chmin(x,y) x = min((x),(y));
#define chmax(x,y) x = max((x),(y));
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
const int INF = 1e9;
const long long LINF = 1e17;
const int MOD = 1000000007;
//const int MOD = 998244353;
const double PI = 3.14159265358979323846;

int main(){
    int p,q,r;
    cin >> p >> q >> r;
    double ans = 0;
    chmax(ans,max(p,q+r)/(double)(p+q+r));
    chmax(ans,max(q,p+r)/(double)(p+q+r));
    chmax(ans,max(r,q+p)/(double)(p+q+r));
    cout << setprecision(20) << ans << endl;
    return 0;
}