online_judge_1047

#include<stdio.h>#include<math.h>int main(){int n,m,i;while(scanf("%d",&n)!=EOF){m=(int)sqrt((float)n);if(n<=1){printf("no\n");continue;}for(i=2;i<=m;i++)if(n%i==0){printf("no\n");break;}if(i>m)printf("yes\n");}return 0;}