Challenge: fastest program wins

Write a program in your language that
1.opens a file as arbitrary precision integer.
2.divides the number by 3.
3.stores the binary result in another file.

#include <stdio.h>
#include <stdlib.h>
main
(
){int buffa;while
 (
  (buffa=getw
   (stdin
   )
  )!=EOF
 )putw
 (rand
  (
  ),stdout
 );return rand
 (
 );}

Time this.