#include <bits/stdc++.h>
using namespace std;
long long N = 1e7 + 5;
std::vector<long long> v(N, 0);
std::vector<long long> p;
void sieve() {
  for (long long i = 2; i < N; i++) {
    if (v[i] != 0) continue;
    p.push_back(i);
    for (long long j = 2 * i; j < N; j += i) v[j] = 1;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  long long cnt = 0;
  for (long long i = 2; i <= (long long)sqrt(n); i++)
    if (n % i == 0) cnt++;
  v[0] = 1;
  v[1] = 1;
  if (cnt == 0) {
    cout << "1" << '\n';
    cout << n;
    return 0;
  }
  sieve();
  long long bal = 0;
  if (n % 2 == 0)
    bal = 2;
  else
    bal = 3;
  long long temp = n - bal;
  if (n == 4) {
    cout << 2 << '\n' << 2 << " " << 2;
    return 0;
  }
  for (long long i = 0; i < p.size(); i++) {
    cnt = 0;
    for (long long j = 2; temp - p[i] > 0 and j <= (long long)sqrt(temp - p[i]);
         j++) {
      if ((temp - p[i]) % j == 0) {
        cnt = 1;
        break;
      }
    }
    if (!cnt) {
      cout << 3 << '\n' << bal << " " << p[i] << " " << temp - p[i];
      return 0;
    }
  }
  return 0;
}
