import java.util.Scanner;
public class Prime {
public static void main(String[] args) {
System.out.println("请输入一个正整数");
Scanner scanner=new Scanner(System.in);
int num=scanner.nextInt();
int i=0;
for (i = 2; i <= num/2; i++) {
if (num % i == 0){
System.out.println(num+"不是素数");
break;
}
}
if (i>num/2){
System.out.println(num+"是素数");
}
}
}