#include <bits/stdc++.h>
using namespace std;
int n, m, k;
double c, x;
int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') {
      f = -1;
    }
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - 48;
    ch = getchar();
  }
  return x * f;
}
int main() {
  int i;
  n = read();
  m = read();
  k = read();
  c = 1.0;
  if (k >= m) {
    cout << 1 << endl;
    return 0;
  }
  for (i = 0; i <= k; i++) {
    x = (m + i - k) * 1.0 / (n + 1 + i);
    c = c * 1.0 * x;
  }
  c = 1.0 - c;
  printf("%.6lf\n", max(c, 0.0));
  return 0;
}
