#include <bits/stdc++.h>
int n, m, k;
int main() {
  scanf("%d %d %d", &n, &m, &k);
  if (n + k < m) {
    puts("0.0000");
    return 0;
  }
  double ans = 1;
  k++;
  for (int i = 1; i <= k; i++) ans *= 1.0 * (m + n + 1 - n - i) / (n + i);
  printf("%.4lf\n", 1.0 - ans);
}
