#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " , ";
  __f(comma + 1, args...);
}
const int N = 1e5 + 5;
const int inf = 1e9;
const long long INF = 1e18;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
bool prime(int x) {
  if (x < 2) return false;
  if (x == 2) return true;
  for (int i = 2; i * i <= x; i++)
    if (x % i == 0) return false;
  return true;
}
int main(int argc, char const* argv[]) {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int n;
  cin >> n;
  if (prime(n)) return cout << 1 << "\n" << n << "\n", 0;
  for (int i = 1; i <= 200; i++) {
    int x = rng() % ((n) - (1) + 1) + (1);
    if (prime(x) && (n - x) > 0 && prime(n - x)) {
      cout << 2 << "\n";
      cout << x << " " << n - x << "\n";
      return 0;
    }
  }
  for (int i = 1; i <= 200; i++) {
    int x = rng() % ((n) - (1) + 1) + (1);
    int cur = n - x;
    if (cur < 5 || !prime(x)) continue;
    for (int j = 1; j <= 200; j++) {
      int y = rng() % ((cur) - (2) + 1) + (2);
      if (prime(y) && (cur - y) > 0 && prime(cur - y)) {
        cout << 3 << "\n";
        cout << x << " " << y << " " << cur - y << "\n";
        return 0;
      }
    }
  }
  return 0;
}
