#include <bits/stdc++.h>

using namespace std;

int m, n, k;
int check(int _x) {
  int mn = _x * 2;
  int nn = _x;
  if (mn < 0 || nn < 0 || m - mn + n - nn < k) {
    return 0;
  }
  return 1;
}

int main() {
  cin >> m >> n >> k;
  int l = 0, r = min(m / 2, n);

  int res = 0;
  while (l < r) {
    int mid = (l + r) / 2;
    if (check(mid)) {
      res = max(res, mid);
      l = mid + 1;
    } else {
      r = mid;
    }
  }
  cout << res << '\n';
}