[cpp
#include
#include
int judge(int n)
{
int i;
i=2;
while(i<=(int)sqrt(n))
{
if(n/i*i==n)
i++;
}
return 1;
}
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
if(n<=1||judge(n)==0)
printf("no\n");
else
printf("yes\n");
}
}