#include <bits/stdc++.h>
using namespace std;
bool isPrime(int n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (int i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
int main() {
  long long n;
  cin >> n;
  if (n % 2 == 0) {
    if (n > 2)
      cout << 2 << endl;
    else
      cout << 1 << endl;
  } else {
    if (n <= 7)
      cout << 1 << endl;
    else {
      if (isPrime(n)) {
        cout << 1 << endl;
      } else {
        if (isPrime(n - 2))
          cout << 2 << endl;
        else
          cout << 3 << endl;
      }
    }
  }
}
