#include <iostream>
#include <vector>
#include <atcoder/convolution>

using namespace std;
using Mint = atcoder::modint998244353;

int main()
{
	int N, S;
	cin >> N >> S;
	Mint Sinv = Mint(S).inv();
	vector<Mint> P;
	for (int i = 0; i < N; ++i)
	{
		int p;
		cin >> p;
		P.push_back(p * Sinv);
	}
	function<vector<Mint>(int, int)> calc = [&](int l, int r)
	{
		if (l == r)
			return vector<Mint>({1, P[l]});
		int m = (l + r) / 2;
		return atcoder::convolution(calc(l, m), calc(m + 1, r));
	};

	auto ret = calc(0, N - 1);
	Mint ans = 0, fact = 1;
	for (int i = 0; i <= N; i++)
	{
		ans += ret[i] * fact;
		fact *= i + 1;
	}

	cout << ans.val() << endl;
}