#include <stdio.h>

  int main()
  {
    /* Sample program. Task: to exchange the contents of two variables.
       It is impossible to accomplish without using an intermediary.
     */
     
     int x, y; /* the two given variables */
     int z;    /* the auxiliary variable  */
     
     /* initialization */
     x=2004;
     y=2005;   
     printf("Initially: x=%d, y=%d\n", x,y);  /* prints: x=2004, y=2005 */
     
     /* swap procedure */
     z=x;   
     x=y;  /* x has changed, but old value is saved in z */
     y=z;  /* copying old value of x into y */
  
     printf("After swap: x=%d, y=%d\n", x,y); /* prints: x=2005, y=2004 */

     return (0);
  }