#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  if (m > n + k)
    cout << 0 << endl;
  else {
    double ans = 1.0;
    for (int i = 1; i <= k + 1; i++) ans *= (double)(m - i + 1) / (n + i);
    printf("%.4lf\n", 1.0 - ans);
  }
  return 0;
}
