Greatest common divisor of three numbers in Haskell

So there is gcd for two numbers, which i know how do define.

gcd a 0 = a

gcd a b = gcd b (a `mod` b)

gcd a b c = gcd3 

How could i define a gcd3 for finding the greatest divisor for three numbers. The definition of gcd3 is:

gcd3 :: Int -> Int -> Int -> Int

>Solution :

You can take the gcd of three numbers the same way you take the sum of three numbers: by doing it two at a time.

gcd3 :: Int -> Int -> Int -> Int
gcd3 x y z = (x `gcd` y) `gcd` z