#include <stdio.h>
#include <math.h>


int i,flag,k,x;
int main ()

{printf("Enter a number\n x=");
scanf("%d", &k);

if ((k>3) && (k<100))
  {i=2; flag=0;
  while ((i<=k/2) && (flag==0))
    {if (k%i==0) flag=1;
       i++;}
         if (flag==0) printf("number %4d is prime \n",k);}

do {(k=pow(k,2));
   (k=k-1);
   (k=k/24);
   printf("x=%d", k);}

return 0;
}