//土尔逊Torson 编写于2023/5/08
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <math.h>
using namespace std;
bool Judge(int x) { //判断是否为质数(素数)
if (x < 2) { //小于2必定不是
return false;
}
int bound = sqrt(x); //确定判定上界
for (int i = 2; i <= bound; ++i) {
if (x%i == 0) {
return false;
}
}
return true;
}
int main() {
int n;
while (scanf("%d", &n) != EOF) {
if (Judge(n)) {
printf("yes\n");
}
else {
printf("no\n");
}
}
system("pause");
return EXIT_SUCCESS;
}
// 64 位输出请用 printf("%lld")