func main()
	var n: int :: cui@inputInt()
	var k: int :: cui@inputInt()
	var x: int :: cui@inputInt()
	var y: int :: cui@inputInt()
	var a: []int :: #[n + 1]int
	for i(1, n)
		do a[i] :: (cui@inputInt() - 1 + k - 1) / k
	end for
	do a.sort()
	do a.reverse()
	
	var mp: int :: y * a[0]
	var ans: int :: mp
	for i(0, n - 1)
		var num: int :: a[i] - a[i + 1]
		do mp :- num * y
		do mp :+ num * (i + 1) * x
		do ans :: lib@min(ans, mp)
	end for
	do cui@print("\{ans}\n")
end func