{Целевой язык не указан, приведу пример на Haskell}

Цена вычисляется как

C - максимальная цена, которую мы можем себе позволить.

Поэтому , где div - оператор целочисленного деления.

Код

• module Spinner (spinner, maybeTo) where
• import Control.Monad.Fail as MFail (MonadFail, fail)
• import System.IO (hFlush, stdout)
• import Text.Read (readMaybe)
• import Data.Maybe (maybe)
• maybeTo :: (MonadFail m) => Maybe b -> String -> m b
• maybeTo Nothing msg = MFail.fail msg
• maybeTo (Just a) _ = return a
• spinner :: IO ()
• spinner = do
•    putStr "Enter an A: "
•    hFlush stdout
•    maybeA <- fmap readMaybe getLine :: IO (Maybe Int)
•    a <- maybeTo maybeA "It's not an Int"
•    putStr "Enter an B: "
•    hFlush stdout
•    maybeB <- fmap readMaybe getLine :: IO (Maybe Int)
•    b <- maybeTo maybeB "It's not an Int"
•    putStr "Enter an C: "
•    hFlush stdout
•    maybeC <- fmap readMaybe getLine :: IO (Maybe Int)
•    c <- maybeTo maybeC "It's not an Int"
•    maybe (putStrLn "You can't use 0 with B var!")
•            (putStrLn . ("The maximum spinner's levers number is  " ++) . show)
•            (makeNumber a b c)
•    putStrLn ""
• makeNumber :: Int -> Int -> Int -> Maybe Int    
• makeNumber _ 0 _ = Nothing
• makeNumber a b c = Just $ div (c - a) b