#include <bits/stdc++.h>
using namespace std;
int n;
int main() {
while (cin >> n) {
if (n == 1) {
cout << "NO" << endl ;
continue ;
}
else {
if (n == 2) {
cout << "YES" << endl ;
continue ;
}
else {
int k = 0;
for (int i = 2; i < n; i ++) {
if (n % i == 0) {
k = 1;
continue ;
}
}
if (k == 1) cout << "NO" << endl ;
else cout << "YES" << endl ;
}
}
}
return 0;
}
当然可以写成函数,来判断一个区间内有几个素数。