#include <bits/stdc++.h>
int main() {
  int m, n, k, t;
  double res, tmp;
  while (scanf("%d%d%d", &n, &m, &k) != EOF) {
    if (n + k < m)
      res = 0;
    else if (k >= m) {
      res = 1;
    } else {
      res = 1;
      tmp = 1;
      for (t = 1; t <= k + 1; t++) {
        tmp *= (double)(m - t + 1) / (n + t);
      }
      res -= tmp;
    }
    printf("%.6f\n", res);
  }
  return 0;
}
