package chelper;

import java.util.ArrayList;
import java.util.List;

import io.InputReader;
import io.OutputWriter;

public class A {
  public void solve(int testNumber, InputReader in, OutputWriter out) {
    int n = in.nextInt();

    List<Integer> res = new ArrayList<>();

    if (n % 2 == 1) {
      res.add(3);
      n -= 3;
    }

    for (int i = 0; i < n / 2; i++) {
      res.add(2);
    }

    out.println(res.size());
    for (int i : res) {
      out.print(i + " ");
    }
  }
}