#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

int main()
{
    int L, i, j, s = 0, flag, count = 0;
    cin >> L;
    for (i = 2; s <= L; i++, flag = 1)
    {
        for (j = 2; j <= int(sqrt(i)); j++)
        {
            if (i % j == 0)
            {
                flag = 0;
                break;
            }
        }
        if (flag == 1)
        {
            if (s+i<=L)
            {
                cout << i << endl;
                s += i;
                count++;
            }
            else
            {
                break;
            }
        }
    }
    cout << count << endl;
    return 0;
}

为什么开启 O2 优化之前20分，开启后ac啊