#include <bits/stdc++.h>
using namespace std;
long double n, m, k, revAns = 1;
int main() {
  cin >> n >> m >> k;
  if (m < k) {
    cout << 1;
  } else {
    for (long double i = 0; i <= k; i++) {
      revAns *= (m - k + i) / (n + i + 1);
    }
    if (revAns > 1.f) {
      cout << 0;
    } else {
      cout << 1.f - revAns;
    }
  }
  return 0;
}
