#include <bits/stdc++.h>
using namespace std;
long long int modpow(long long int a, long long int n, long long int temp) {
  long long int res = 1, y = a;
  while (n > 0) {
    if (n & 1) res = (res * y) % temp;
    y = (y * y) % temp;
    n /= 2;
  }
  return res % temp;
}
long long int prime[100006];
long long int M[100005];
long long int check(long long int val) {
  if (val == 0 || val == 1) return 0;
  long long int sq = sqrt(val);
  long long int i;
  for (i = 2; i <= sq; i++) {
    if (val % i == 0) return 0;
  }
  return 1;
}
int main() {
  long long int i, j, n, t, k;
  vector<long long int> pr;
  for (i = 2; i <= 6000; i++) {
    for (j = 2 * i; j <= 6000; j += i) {
      prime[j] = 1;
    }
  }
  for (i = 2; i <= 6000; i++) {
    if (!prime[i]) {
      pr.push_back(i);
    }
  }
  long long int ln = int(pr.size());
  scanf("%lld", &n);
  if (n <= 7) {
    if (n == 3) {
      cout << 1 << endl;
      cout << 3 << endl;
    } else if (n == 7) {
      cout << 2 << endl;
      cout << 5 << " " << 2 << endl;
    } else if (n == 5) {
      cout << 2 << endl;
      cout << 3 << " " << 2 << endl;
    }
  } else {
    for (i = 0; i < ln && pr[i] < n; i++) {
      for (j = i + 1; j < ln && pr[j] < n; j++) {
        long long int cur = n - pr[i] - pr[j];
        if (check(cur)) {
          cout << 3 << endl;
          cout << pr[i] << " " << pr[j] << " " << cur << endl;
          return 0;
        }
      }
    }
  }
  return 0;
}
