module Main where

solve :: Int -> Int -> Int -> Int -> Int
solve p d m s = let price = max p m in
  if price <= s then 1 + solve (p - d) d m (s - price) else 0

readInt :: String -> Int
readInt = read

main :: IO ()
main = interact $ show . (\[p, d, m, s] -> solve p d m s) . map readInt . words