#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
template <class c>
struct rge {
  c b, e;
};
template <class c>
rge<c> range(c i, c j) {
  return rge<c>{i, j};
}
template <class c>
auto dud(c* x) -> decltype(cerr << *x, 0);
template <class c>
char dud(...);
struct debug {
  template <class c>
  debug& operator<<(const c&) {
    return *this;
  }
};
const long long MOD = 1e9 + 7;
const long long N = 1e6 + 10;
const long long INF = 1e18 + 10;
bool isPrime(long long x) {
  if (x <= 1) return false;
  for (long long i = 2; i * i <= x; i++) {
    if (x % i == 0) return false;
  }
  return true;
}
vector<bool> prime(N, true);
vector<long long> primes;
void seive() {
  prime[0] = prime[1] = false;
  for (long long i = 2; i * i <= N; i++) {
    if (prime[i]) {
      for (long long j = i + i; j < N; j += i) prime[j] = false;
    }
  }
  for (long long i = 0; i < N; i++) {
    if (prime[i]) {
      primes.emplace_back(i);
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  seive();
  long long n;
  cin >> n;
  if (isPrime(n)) {
    cout << 1 << endl;
    cout << n << endl;
    return 0;
  }
  long long cur = n;
  while (cur--) {
    if (isPrime(cur)) {
      debug() << " ["
              << "cur"
                 ": "
              << (cur) << "] ";
      if (cur + 2 == n) {
        cout << 2 << endl;
        cout << 2 << ' ' << cur << endl;
        return 0;
      }
      int target = n - cur;
      debug() << " ["
              << "target"
                 ": "
              << (target) << "] ";
      int L = 0, R = (int)primes.size() - 1;
      while (L <= R) {
        if (primes[L] + primes[R] == target) {
          cout << 3 << endl;
          cout << primes[L] << ' ' << primes[R] << ' ' << cur << endl;
          return 0;
        } else if (primes[L] + primes[R] > target)
          R--;
        else {
          debug() << " ["
                  << "L"
                     ": "
                  << (L)
                  << "] "
                     " ["
                  << "R"
                     ": "
                  << (R) << "] ";
          debug() << " ["
                  << "primes[L]"
                     ": "
                  << (primes[L])
                  << "] "
                     " ["
                  << "primes[R]"
                     ": "
                  << (primes[R]) << "] ";
          L++;
        }
      }
    }
  }
  return 0;
}
