#include <bits/stdc++.h>
using namespace std;
int n, m, k;
long long cc[200009];
long long c(int n, int m) {
  printf("*%d %d %lld %lld %lld*\n", n, m, cc[n], cc[m], cc[n - m]);
  return cc[n] / cc[m] / cc[n - m];
}
double js(int n, int m, int k) {
  int a = 2, b = 2;
  long long ans = 1;
  printf("!%lld!\n", ans);
  for (int j = 1; j <= n; j++) {
    ans *= j;
    if (ans == 0) {
      return 0;
    }
    while (a <= m - k - 1 && ans % a == 0) {
      ans /= a;
      a++;
    }
    while (b <= n + k + 1 && ans % b == 0) {
      ans /= b;
      b++;
    }
  }
  for (int j = 1; j <= m; j++) {
    ans *= j;
    while (a <= m - k - 1 && ans % a == 0) {
      ans /= a;
      a++;
    }
    while (b <= n + k + 1 && ans % b == 0) {
      ans /= b;
      b++;
    }
  }
  double da = ans;
  while (a <= m - k - 1) {
    da /= a;
    a++;
  }
  while (b <= n + k + 1) {
    da /= b;
    b++;
  }
  return da;
}
int main() {
  scanf("%d%d%d", &n, &m, &k);
  cc[0] = cc[1] = 1;
  for (int j = 2; j <= 200001; j++) cc[j] = cc[j - 1] * j;
  if (n + k < m) {
    printf("0");
    return 0;
  }
  if (k >= m) {
    printf("1");
    return 0;
  }
  double ans = 1;
  for (int j = 1; j <= k + 1; j++) ans = ans * (m - k - 1 + j) / (n + j);
  printf("%.4lf", 1 - ans);
  return 0;
}
