题解，大家应该都看得懂

#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;
}