#include <bits/stdc++.h>
using namespace std;
bool prime(int n) {
  for (int i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
int main() {
  int n;
  cin >> n;
  if (prime(n)) {
    cout << 1 << "\n" << n << endl;
    return 0;
  }
  if (prime(n - 2)) {
    cout << 2 << "\n" << 2 << "\n" << n - 2 << endl;
    return 0;
  }
  cout << 3 << "\n" << 3 << endl;
  n -= 3;
  for (int i = 2; i <= n; i++) {
    if (prime(i) and prime(n - i)) {
      cout << i << "\n" << n - i << endl;
      break;
    }
  }
  return 0;
}
