#include <bits/stdc++.h>
using namespace std;
#define INF 1000000000
#define MOD 1000000007
#define FOR(i, a, b) for(int i = (int)(a); i < (int)(b); i++)
#define REP(i, b) FOR(i, 0, b)
#define ALL(x) (x).begin(),(x).end()
typedef long long ll;
#define endl '\n'

int main() {
  double p, q, r;
  cin >> p >> q >> r;
  double pq = p + q, qr = q + r, rp = r + p, pqr = pq + r;
  cout << max(max(pq / pqr, qr / pqr), rp / pqr);
  cout << endl;
  return 0;
}