* File: composites.c */
#include <stdio.h>
#include <math.h>        /*Header file for sqrt function*/
#define N 30      
main()
{
      int n,i,l,k,j;
      n=3;
      i=3;
      k=3;
      l=1;
      j=1;
      while(l<=N)
      {
                  while(j!=l||l==1)
                  {
                             while((n%i!=0&&i<=(double)sqrt(n))||n==i)
                            { 
                                i=i+2;
                            }
                            if(n%i!=0&&i>(double)sqrt(n))
                            {
                                     if(n-k-1==l)
                                     {                     
                                           printf("first %d consecutive composites from %d to %d \n",l,k+1,n-1);
                                           l=l+2;
                                           j=l;
                                     }
                             }
                             if(l!=1&&n%i!=0&&i>(double)sqrt(n))
                             {
                                k=n; 
                             }
                             i=3;
                             n=n+2;
                  }
                  n=3;
       };
      getchar();
}