#include <bits/stdc++.h>
using namespace std;
bool prime(long long int n) {
  for (long long int i = 2; i <= sqrt(n * 1.0); i++) {
    if (n % i == 0) return false;
  }
  return true;
}
long long int ne_prime(long long int n) {
  for (long long int j = 2; j <= 1000; j += 2) {
    if (prime(n - j)) return (n - j);
  }
}
vector<long long int> p;
void s_prime() {
  long long int x[1001];
  for (long long int i = 0; i < 1001; i++) x[i] = 1;
  x[0] = x[1] = 0;
  for (long long int i = 2; i < 1001; i++) {
    if (x[i]) {
      for (long long int j = 2 * i; j < 1001; j += i) {
        x[j] = 0;
      }
    }
  }
  for (long long int i = 0; i < 1001; i++) {
    if (x[i]) p.push_back(i);
  }
}
int main() {
  long long int n;
  cin >> n;
  s_prime();
  if (prime(n)) {
    cout << 1 << endl;
    cout << n;
    return 0;
  }
  if (prime(n - 2)) {
    cout << 2 << endl;
    cout << 2 << " " << (n - 2);
    return 0;
  }
  if (prime(n - 4)) {
    cout << 3 << endl;
    cout << 2 << " " << 2 << " " << (n - 4);
    return 0;
  }
  cout << 3 << endl;
  long long int k = ne_prime(n);
  cout << k << " ";
  long long int d = n - k;
  if (prime(d)) {
    cout << d;
    return 0;
  }
  for (long long int i = 0; i < p.size(); i++) {
    long long int d1 = d - p[i];
    if (d1 <= 1) break;
    for (long long int j = 0; j < p.size(); j++) {
      if (p[j] == d1) {
        cout << p[i] << " " << p[j];
        return 0;
      }
    }
  }
  return 0;
}
