我原本是不费的，后面@闪电九尾狐帮助me找出了错误，还真的要谢谢他/她

#include <bits/stdc++.h>

using namespace std;

long long number;
bool flag = true;

int main() {
    cin >> number;
    
    if (number == 1) {
        flag = false;
    }
    for (int i = 2 ; i < number ; i++) {
        
        if (number % i == 0) {
            flag = false;
            break;
        }else {
            flag = true;
        }
    }

    if (!flag || number == 1) {
        cout << "No" << endl;
    }else {
        cout << "Yes" << endl;
    }
    
    return 0;
}