import java.math.BigInteger;
import java.util.Scanner;

public class Main{

	static Scanner s=new Scanner(System.in);

	public static void main(String __[]){
		input();
		solve(s.nextInt());
	}

	private static void input(){
	}

	private static void solve(int in){
		BigInteger inb=BigInteger.valueOf(in);
		if(inb.equals(BigInteger.ONE)){
			System.out.println("NO");
			return;
		}
		for(BigInteger bi=BigInteger.ONE.add(BigInteger.ONE); bi.intValue()<in; bi=bi.add(BigInteger.ONE)){
			if(inb.mod(bi).equals(BigInteger.ZERO)) {
				System.out.println("NO");
				return;
			}
		}
		System.out.println("YES");
	}
}