/* eratostenovo sito v1.1 */

void main()
{
   long int polje[10000];
   unsigned long int x,trg;

   for (x=0; x<=10000; x++) polje[x]=0;

   for (x=2; x<=10000; x++)
   {
	 if (!polje[x])
	 {
	   unsigned long int i;
	   for (i=x+x; i<=9999; i+=x) polje[i]=1;
	 }
   }

  scanf("%d", &trg);
  if (!polje[trg]) printf("prost broj!\n");
}