func main()
	var n: int :: cui@inputInt()
	var x: int :: cui@inputInt()
	var a: int :: cui@inputInt()
	var b: int :: cui@inputInt()
	var ans: int :: (x + a - 1) / a
	do ans :: [ans, (2 ^ (n - 1) - x + b - 1) / b].min()
	do cui@print("\{ans}\n")
end func