> #include <stdio.h>
> #include <string.h>
> #include <malloc.h>
> 
> void main ()
> {
>    char *back[10], *forward[10], *p, *q;
>    int  i = -1, j = -1; 
>    q = (char*)malloc (50*sizeof(char));
>    q = "http://www.acm.org/";
>    p = (char*)malloc (10*sizeof(char)); 
>    scanf("%s",p);
>   
>    while (strcmp(p, "QUIT") != 0)
>    {
> 	  
> 	   if(strcmp (p , "VISIT") == 0)
> 	   {
> 		   
> 		   back[++i] = q;
> 	       q = (char*)malloc (50*sizeof(char));
> 		   scanf("%s",q); 
> 		   puts(q);
> 		   j = -1;
> 	   }
> 	  if (strcmp (p, "BACK") == 0)
> 	        if (i > -1)
> 			    {
> 				 forward[++j] =  q;
> 				  q = back[i--];
> 				puts(q);
> 			  }
>              else
> 				 printf ("Ignored\n");
> 			 
> 	  if (strcmp(p, "FORWARD") == 0 )
> 		     if (j > -1)
> 			 {
> 			   back[++i] = q;
> 			   q = forward[j--];
> 			   puts(q);
> 			 } 
> 		     else 
> 				 printf ("Ignored\n");
> 		     
> 		   memset(p, 0, 10);
> 	       scanf("%s",p);
>    }
> 
>    
> }