#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>#include <cmath>using namespace std;const int Max=50000;bool prime[Max+1];int isprime[Max];int main(){	memset(prime,true,sizeof(prime));	prime[0]=prime[1]=false;	int e=(int)sqrt(1.0*Max);	int cp=0;	for(int i=2;i<=e;i++){		if(prime[i]){			for(int j=i+i;j<=Max;j+=i)			prime[j]=false;		}	}	for(int i=0;i<=Max;i++)	if(prime[i])	isprime[cp++]=i;	int n;	while(scanf("%d",&n)!=EOF){		if(n==1) { printf("NO\n"); continue; }		int c=0; 		int lim;		lim=sqrt(n*1.0);		bool flag=true;		for(int i=0;i<cp;i++)		if(isprime[i]<=lim)		if(n%isprime[i]==0)		flag=false;		if(flag)printf("YES\n");		else printf("NO\n");	}	return 0;}