#include <bits/stdc++.h>
using namespace std;
int n, m, k;
int main() {
  int i, j;
  while (scanf("%d %d %d", &n, &m, &k) != EOF) {
    if (m > n + k) {
      printf("0.0000\n");
      continue;
    }
    if (k >= n) {
      printf("1.0000\n");
      continue;
    }
    double ans = 1;
    for (i = 0; i <= k; i++) {
      ans *= m - i;
      ans /= n + i + 1;
    }
    printf("%.4lf\n", 1.0 - ans);
  }
}
