#include <iostream>
using namespace std;
unsigned long long int a, dem;
bool kt = false;
int main() 
{
    cin >> a;
    while(a > 1)
    {
        if(a % 2 == 0)
        {
            dem += a/2;
            a = 1;
        }
        else
        {
            a -= 3;
            kt = true;
        }
    }
    if(kt) cout << dem + 1 << "\n";
    else cout << dem << "\n";
    for(int i = 0; i < dem; i++)
    {
        
        cout << "2 ";
    }
    if(kt) cout << 3;
    return 0;
}

$#khanhtaon$