#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(),(x).end()

typedef long long ll;
typedef pair<ll, ll> P;

const int mod =  1000000007;  //出力は (ans % mod + mod) % mod  (負の剰余を正にする)
const int inf = 1e9;
const long long INF = 1LL << 60;

int main()
{
    double p,q,r; cin >> p >> q >> r;
    double a = max({p+q,p+r,q+r});
    printf("%.8lf\n",a/(p+q+r));
}