#include <bits/stdc++.h>
using namespace std;
long long mulmod(long long a, long long b, long long c) {
  long long x = 0, y = a % c;
  while (b > 0) {
    if (b % 2 == 1) {
      x = (x + y) % c;
    }
    y = (y * 2) % c;
    b /= 2;
  }
  return x % c;
}
int modulo(int a, int b, int c) {
  long long x = 1, y = a;
  while (b > 0) {
    if (b % 2 == 1) {
      x = (x * y) % c;
    }
    y = (y * y) % c;
    b /= 2;
  }
  return x % c;
}
bool Miller(long long p, int iteration) {
  if (p < 2) {
    return false;
  }
  if (p != 2 && p % 2 == 0) {
    return false;
  }
  long long s = p - 1;
  while (s % 2 == 0) {
    s /= 2;
  }
  for (int i = 0; i < iteration; i++) {
    long long a = rand() % (p - 1) + 1, temp = s;
    long long mod = modulo(a, temp, p);
    while (temp != p - 1 && mod != 1 && mod != p - 1) {
      mod = mulmod(mod, mod, p);
      temp *= 2;
    }
    if (mod != p - 1 && temp % 2 == 0) {
      return false;
    }
  }
  return true;
}
bool isPrime(long long int n) { return Miller(n, 60); }
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  ;
  long long int n;
  cin >> n;
  if (n == 3) {
    cout << 1 << endl;
    cout << 3 << endl;
    return 0;
  }
  if (n == 5) {
    cout << 1 << endl;
    cout << 5 << endl;
    return 0;
  }
  if (n == 7) {
    cout << 1 << endl;
    cout << 7 << endl;
    return 0;
  }
  if (n == 9) {
    cout << 3 << endl;
    cout << 3 << " " << 3 << " " << 3 << endl;
    return 0;
  }
  cout << 3 << endl;
  cout << 3 << " ";
  n = n - 3;
  for (long long int i = 2; i <= n; i++) {
    if (isPrime(i) && isPrime(n - i)) {
      cout << i << " " << (n - i) << endl;
      return 0;
    }
  }
  return 0;
}
