#include <stdio.h>
#include <stdlib.h>

#define X 0
#define Y 2
#define Z 5

/*
slot 0: X
slot 1: always zero, let's us know X is before it
slot 2: Y
slot 3: always one, let's us know Y is before it
slot 4: always zero, used to terminate loops
slot 5: Z
*/

int main(int argc, char **argv)
 {
   short int vars[5];
   short int *p = vars;

   if(argc != 3)
    {
      fprintf(stderr, "Usage: %s X-value Y-value\n", argv[0]);
      exit(1);
    }
   vars[X] = atoi(argv[1]); /* set X */
   vars[Y] = atoi(argv[2]); /* set Y */

   p++; /* point to slot 1 */
   while(*p)
    {
      (*p)--; /* initialize slot 1 to zero */
    }
   p++;p++; /* point to slot 3 */
   while(*p)
    {
      (*p)--; /* set slot 3 to zero */
    }
   (*p)++;    /* set slot 3 to one */
   p++;     /* point to slot 4 */
   while(*p)
    {
      (*p)--; /* initialize slot 4 to zero */
    }
   p--;p--;p--;p--; /* point to X */
   while(*p) /* while X */
    {
      p++;p++;p++;p++;p++; /* point to Z */
      while(*p)
       {
         (*p)--;              /* set Z to 0 */
       }
      p--;p--;p--;         /* point to Y */
      while(*p)            /* if Y is nonzero, set Z to 1 */
       {
         (*p)--;           /* decrement Y */
         p++;p++;p++;      /* point to Z */
         (*p)++;             /* Z = 1 */
         p--;              /* point to slot 4 which is always zero */
       }                   /* loop terminates after 1 iteration */
      p--;                 /* point to either slot 1 or slot 3 */
      while(*p)
       {
         /* if we are here, we are pointing to slot 3 */
         p--;p--;          /* point to slot 1 */
       }
      p--;                 /* point to X */
      (*p)--;                /* decrement X */
    }
   p++;p++;p++;p++;p++;    /* point to Z */
   while(*p)
    {
      printf("Y >= X\n");
      p--;                 /* point to slot 4, always zero */
    }
   return 0;
 }