(defun merge (list1 list2)
    (if list1
        (if list2
            (if (<=(car list1)(car list2))
                (cons
                    (car list1)
                    (cons
                        (car list2)
                        (merge (cdr list1)(cdr list2))
                    )
                )
                (cons
                    (car list2)
                    (cons
                        (car list1)
                        (merge (cdr list1)(cdr list2))
                    )
                )
            )
        list1
        )
    list2
    )
)