#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  while (scanf("%d%d%d", &n, &m, &k) != EOF) {
    double ret = 1;
    for (int i = 0; i <= k; i++) {
      ret = ret * (m - i) / (n + i + 1);
    }
    ret = 1 - ret;
    if (ret < 0) ret = 0;
    printf("%.9lf\n", ret);
  }
  return 0;
}
