#include <bits/stdc++.h>
using namespace std;
bool is_prime(int x) {
  for (int i = 2; i <= sqrt(x); i++)
    if (x % i == 0) return 0;
  return 1;
}
int main() {
  int n;
  cin >> n;
  if (is_prime(n))
    cout << "1" << endl;
  else if (n % 2 == 0)
    cout << "2" << endl;
  else if (n & 1 && is_prime(n - 2))
    cout << "2" << endl;
  else
    cout << "3" << endl;
  return 0;
}
