#include <bits/stdc++.h>
using namespace std;
int n, m, k;
int l;
long double calc() {
  long double a = 1;
  for (int i = 1; i <= k + 1; i++) {
    a *= ((1.0) * (m - i + 1) / (n + i));
  }
  return 1.0 - a;
}
int main() {
  cin >> n >> m >> k;
  l = k - m + n;
  if (l < 0) {
    cout << 0;
    return 0;
  }
  if (m <= k) {
    cout << 1;
    return 0;
  }
  cout << calc();
  return 0;
}
