#include <bits/stdc++.h>
using namespace std;
template <typename T>
T nextInt() {
  T x = 0, p = 1;
  char ch;
  do {
    ch = getchar();
  } while (ch <= ' ');
  if (ch == '-') {
    p = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + (ch - '0');
    ch = getchar();
  }
  return x * p;
}
const int maxN = (int)3e5 + 10;
const int INF = (int)1e9;
const int mod = (int)1e9 + 7;
const long long LLINF = (long long)1e18;
int n;
bool isPrime(int x) {
  if (x == 1) return false;
  for (int i = 2; i * i <= x; ++i) {
    if (x % i == 0) return false;
  }
  return true;
}
void answer(int x) {
  cout << 1 << '\n';
  cout << x << '\n';
  exit(0);
}
void answer(int x, int y) {
  cout << 2 << '\n';
  cout << x << ' ' << y << '\n';
  exit(0);
}
void answer(int x, int y, int z) {
  cout << 3 << '\n';
  cout << x << ' ' << y << ' ' << z << '\n';
  exit(0);
}
int main() {
  cin >> n;
  if (isPrime(n)) answer(n);
  if (isPrime(n - 2)) answer(2, n - 2);
  for (int x = n;; x--) {
    if (!isPrime(x)) continue;
    int v = n - x;
    if (isPrime(v)) answer(v, x);
    for (int a = 2; a <= v; ++a) {
      if (isPrime(a) && isPrime(v - a)) {
        answer(x, a, v - a);
      }
    }
  }
  return 0;
}
