#include <stdio.h>

void exit(int);

   typedef struct webpage {
       int              wpnumber;   // Web page id
       struct webpage*  nextwp;     // Pointer to web page
       struct itarray        {
             int             indexterm;  // Indexterm
             struct webpage* wplink;     // Pointer to web page
         } itl[2];
     } Webpage;

   typedef struct indexterm {
       int                itnumber;       //Index term id
       int                numberoftimes;  //# of web pages that include itnumber
       Webpage*           link2webpage;   //Pointer to web page
       struct indexterm* nextit;          //Pointer to index term
     } Indexterms;

// The following function takes as input a pointer to the first element
// in the web pages list and an integer m and returns a pointer to the
// instance of struct webpage that represent web page m, or NULL (zero)
// if the web page is not in the list.

struct webpage *find(struct webpage *p, int m)
{struct webpage *q;
 if (p == NULL) return NULL;
 q = p;
 while (q != NULL)
  { if (q->wpnumber == m) return q;
    if (q->wpnumber > m) return NULL;
    if (q->wpnumber < m) q = q->nextwp;
  }
 return q;
}

int main(void) 
{ int m,i1,i2;
  char t;
  // ...
  while(1==1)
   {t=getchar();
    switch(t) {
     case('i'): {scanf("%d %d %d",&m,&i1,&i2);
                 printf("i %d %d %d\n", m, i1, i2);
                 /* Should invoke a function to insert a web page*/
                 break;}
     case('d'): {scanf("%d",&m);
                 printf("d %d\n",m);
                 /* Should invoke a function to delete a web page */
                 break;}
            //  ...
     case('l'): {printf("l\n");
                 /* Should invoke a function to print the correct number */
                 break;}
            //  ...
     case('q'): {printf("q\n"); // need to delete lists
                 exit(0);}
    }
  if('\n' != getchar()) exit(1);
   }
}

// The following function takes as input a pointer to the first element
// in the index terms list and an integer i1, and returns the number
// of web pages containing index term i1.  If the index term is not
// in the system, it returns zero.

int count(struct indexterm *ip, int i1)
{struct indexterm *iq;
 struct webpage *q;
 int counter;
 // Find first web page
 if (ip == NULL) return 0;
 iq = ip;
 while (iq != NULL)
  { if (iq->itnumber == i1) break;
    if (iq->itnumber > i1) return 0;
    if (iq->itnumber < i1) iq = iq->nextit;
  }
 if (iq == NULL) return 0;
 // Found the first web page so now count all the
 // web pages that contian index term i1
 counter = 0;
 q = iq->link2webpage;
 while (q != NULL)
  {counter++;
   if (i1 == q->itl[0].indexterm) q = q->itl[0].wplink;
             else q = q->itl[1].wplink;
  }
 return counter;
}