#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-10;
const int MAX = 1e5 + 10;
int main() {
  int n, m, k;
  while (scanf("%d %d %d", &n, &m, &k) == 3) {
    double res = 1;
    for (int i = 0; i < k + 1; i++) {
      res *= (double)(m - k + i) / (double)(n + i + 1);
    }
    if (1 - (res) < eps)
      printf("0\n");
    else
      printf("%.10lf\n", 1.0 - res);
  }
  return 0;
}
