#include <bits/stdc++.h>
using namespace std;
template <class T>
bool ckmax(T& x, T y) {
  return x < y ? x = y, 1 : 0;
}
template <class T>
bool ckmin(T& x, T y) {
  return x > y ? x = y, 1 : 0;
}
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') f = 0;
    ch = getchar();
  }
  while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
  return f ? x : -x;
}
int n, m, k;
signed main() {
  cin >> n >> m >> k;
  if (n + k < m)
    puts("0.000000");
  else if (k >= m)
    puts("1.000000");
  else {
    double ans = 1;
    for (int i = 0; i <= k; ++i) ans *= (double)(m - k + i) / (n + 1 + i);
    ans = 1 - ans;
    printf("%.6lf\n", ans);
  }
}
