Input: A non$-$negative integer

$(1)$ if

then return $1$

$(2)$ let

$(3)$ let

$(4)$ repeat

$--($a$)$ let

$--($b$)$ let

$(5)$ until

$(6)$ return

What does the algorithm return when the input is

$?$

What does the algorithm return when the input is

$?$

What does the algorithm return when the input is

$?$

What does the algorithm return when the input is a non$-$negative integer

$?$

A$.$

B$.$

C$.$

D$.$ The greatest common divisor of

and

E$.$ The remainder of the division of

by

$.$

F$.$ The difference of the first

natural numbers and $4.$