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: num@BigInt :: num@makeBigIntFromInt(y * a[0])
	var ans: num@BigInt :: mp
	for i(0, n - 1)
		var numDiff: num@BigInt :: num@makeBigIntFromInt(a[i] - a[i + 1])
		do mp :: mp.sub(numDiff.mulInt(y))
		do mp :: mp.add(numDiff.mulInt((i + 1) * x))
		do ans :: [ans, mp].min()
	end for
	do cui@print("\{ans}\n")
end func