main :: IO()
main = do
   print $ removeFistOccurrence 110 1 == 10
   print $ removeFistOccurrence 15365 5 == 1536
   print $ removeFistOccurrence 15360 0 == 1536
   print $ removeFistOccurrence 15300 0 == 1530
   print $ removeFistOccurrence 15365 1 == 5365
   print $ removeFistOccurrence 35365 3 == 3565
   print $ removeFistOccurrence 1212 1 == 122
   print $ removeFistOccurrence 1212 2 == 121
   print $ removeFistOccurrence (removeFistOccurrence 1212 1) 1 == 22

removeFistOccurrence :: Int -> Int -> Int
removeFistOccurrence d n = helper 0 0 n
 where
    helper result pow number
     | number == 0 = result
     | mod number 10 /= d = helper (mod number 10 * 10^pow + result) (pow + 1) (div number 10)
     | otherwise = helper result pow (div number 10)