#include <bits/stdc++.h>
using namespace std;
int n, m, k;
double dp[2][100100];
int lo, hi;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> m >> k;
  dp[0][k] = 1.00000;
  lo = k;
  hi = k;
  double p, q, r;
  for (int i = 0; i < (n + m); i++) {
    int cur = i % 2;
    int nxt = (i + 1) % 2;
    for (int j = lo - 1; j <= hi + 1; j++) {
      if (j >= 0) dp[nxt][j] = 0.0000;
    }
    q = (n * 2 + k - i) / 2.0 / (n + m - i);
    r = 0.5 / (n + m - i);
    for (int j = lo; j <= hi; j++) {
      p = q - j * r;
      if (j > 0) dp[nxt][j - 1] += dp[cur][j] * (1 - p);
      dp[nxt][j + 1] += dp[cur][j] * p;
    }
    if (lo > 0) lo--;
    while (lo < hi && dp[nxt][lo] < 1e-12) lo++;
    hi++;
    while (hi > lo && dp[nxt][hi] < 1e-12) hi--;
  }
  double tot = 0.0000;
  for (int i = lo; i <= hi; i++) tot += dp[(n + m) % 2][i];
  cout << fixed << setprecision(12) << tot << endl;
  return 0;
}
