#include<stdio.h>
#include<stdlib.h>

typedef long long int ln;

int main(void){

	ln N;
	scanf("%lld",&N);

	if(N==1){
		printf("NO\n");
		return 0;
	}

	ln k;
	k=2;
	int count;
	count=0;
	while(k*k<=N && count < 2){
		if(N%k==0){
			count++;
		}
		k++;
	}

	if(count==2){
		printf("YES\n");
	} else {
		printf("NO\n");
	}

	return 0;
}