residue of division

module Main where
import IO

– function ost(a,b) returns residue of division of A number by B number
ost :: Integer -> Integer -> Integer
ost a b | a >= b = ost (a-b) b
ost a b | a < b = a

readNum :: IO Integer
readNum = readLn

main = do
hSetBuffering stdout NoBuffering
putStr “Enter A: ”
a <- readNum
putStr “Enter B: ”
b <- readNum

putStr (“residue of division of the A number by the B number = ” ++ show (ost a b) ++ “\n”)