#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-10;
const int oo = ~0u >> 2, mo = (int)1e9 + 7;
const int mn = 510;
int n, m, k;
int main() {
  cin >> n >> m >> k;
  double Ans = 1;
  for (int i = 0; i <= k; ++i) Ans *= 1. * (m - i) / (n + i + 1);
  cout << fixed << setprecision(10) << max(0., 1 - Ans) << endl;
}
