#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, m, k;
  cin >> n >> m >> k;
  double ans = 1.0;
  if ((n + k) < m) {
    cout << "0" << endl;
    return 0;
  }
  for (int i = 0; i <= k; i++) {
    ans = ans * ((m - i) / (n + i + 1));
  }
  double v = 1 - ans;
  std::cout << std::setprecision(5) << v << '\n';
}
