题解 大家应该都能懂

#include<iostream>
using namespace std;
int main(){
    int N;
    cin >> N;
    if(N == 1){
        cout<<"No";
    }else {
        bool flag = true;
        for(int i = 2;i < N;i++){
            if( N % i == 0) {
                flag = false;
                break;
            }
        }
        if(flag == false) {
            cout <<"No";
        } else {
            cout <<"Yes";
        }
    }
    return 0;
}