import java.lang.reflect.Method;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws Exception {
		BigInteger n = new Scanner(System.in).nextBigInteger();
		Method ipp = n.getClass().getMethod("isProbablePlime".replace("li", "ri"), int.class);
		System.out.println((boolean) ipp.invoke(n, (int) Math.PI) ? "YES" : "NO");
	}

}