#include <bits/stdc++.h>
int main() {
  int n, m, k;
  scanf("%d%d%d", &n, &m, &k);
  double ans;
  if (k >= m)
    ans = 1.0;
  else if (n + k < m)
    ans = 0.0;
  else {
    ans = 1.0;
    for (int i = 0; i <= k; ++i) ans = ans * (m - i) / (n + i + 1);
    ans = 1 - ans;
  }
  printf("%.5lf", ans);
  return 0;
}
