Write a LISP Program to Find GCD of Two Numbers

(DEFUN GCD(X Y)
(COND((OR(=X 0)(=Y 0)) 0)
(( ((X Y) (GCD-POSITIVE(-X Y)Y))
(T(GCD-POSITIVE X(-Y X)))))
(DEFUN MAIN(X Y) # Main Program
(GCD X Y))