#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  long double ans = 1;
  for (int i = 0; i <= k; i++)
    ans *= 1.0 * (long double)(m - i) / (long double)(n + i + 1);
  cout << max((long double)0.0000, 1.00 - ans) << endl;
  return 0;
}
