#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const long long mod2 = 998244353;
const long long N = 2e6;
const long long inf = 1e18;
template <typename... T>
void read(T&... args) {
  ((cin >> args), ...);
}
template <typename... T>
void write(T&&... args) {
  ((cout << args << " "), ...);
}
template <typename... T>
void writeline(T&&... args) {
  ((cout << args << " "), ...);
  cout << "\n";
}
long long add(long long a, long long b, long long mod) {
  long long res = (a + b) % mod;
  return (res < 0) ? res + mod : res;
}
long long mul(long long a, long long b, long long mod) {
  long long res = (a * 1LL * b) % mod;
  return (res < 0) ? res + mod : res;
}
string binary(long long x) {
  string res = "";
  for (long long i = 0; i < 32; i++) res += (1 << i & x) ? '1' : '0';
  return res;
}
long long in(long long x, long long y, long long z) {
  if (y > z) swap(y, z);
  return (x >= y && x <= z);
}
bool isPrime(long long x) {
  for (long long i = 2; i * i <= x; i++) {
    if (x % i == 0) return false;
  }
  return true;
}
void solve() {
  long long n;
  cin >> n;
  long long m = n;
  while (!isPrime(m)) m--;
  if (m == n) {
    cout << 1 << "\n";
    cout << n;
  } else if (m + 2 == n) {
    cout << 2 << "\n";
    write(2, m);
  } else {
    long long i = 2;
    while (!isPrime(i) || !isPrime(n - m - i)) i++;
    cout << 3 << "\n";
    write(i, n - m - i, m);
  }
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
