#include <bits/stdc++.h>
using namespace std;
const long long int Maxn3 = 1e3 + 10;
const long long int Maxn4 = 1e4 + 10;
const long long int Maxn5 = 1e5 + 10;
const long long int Maxn6 = 1e6 + 10;
const long long int Maxn7 = 1e7 + 10;
const long long int Maxn8 = 1e8 + 10;
const long long int Maxn9 = 1e9 + 10;
const long long int Maxn18 = 1e18 + 10;
const long long int Mod1 = 1e7 + 7;
const long long int Mod2 = 1e9 + 7;
const long long int LLMax = LLONG_MAX;
const long long int LLMin = LLONG_MIN;
const long long int INTMax = INT_MAX;
const long long int INTMin = INT_MIN;
long long int mn = LLMax, mx = LLMin;
bool prime(int x) {
  for (int i = 2; i * i <= x; i++)
    if (x % i == 0) return 0;
  return 1;
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  int n;
  cin >> n;
  if (prime(n) == 1)
    return cout << "1\n" << n, 0;
  else {
    cout << "3\n3 ";
    n -= 3;
    for (int i = 3; i < n; i += 2)
      if (prime(n - i) and prime(i)) return cout << i << ' ' << n - i, 0;
  }
  return 0;
}
