#include <stdio.h>

main(int argc, char ** argv)
{  int low, high, guess, response, count;

   low = 1;
   high = 100;
   count = 0;
  
   while(1)
   {  guess = (high+low)/2;
      count = count+1;
      printf("I guess %d.\n",guess);
      printf("Am I correct (0), high (1) or low (2)? ");
      scanf("%d", &response);
      if(response==0)
       break;
      switch(response)
      {  case 1: high = guess; break;
         case 2: low = guess; break;
         default: printf("I don't understand %d.\n",response);
                  count = count-1;
      }
   }
   printf("I took %d guesses.\n",count);
}