#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001
using A = array<vector<mint>,2>;
struct combi{
	deque<mint> kaijou;
	deque<mint> kaijou_;
	
	combi(int n){
		kaijou.push_back(1);
		for(int i=1;i<=n;i++){
			kaijou.push_back(kaijou[i-1]*i);
		}
		
		mint b=kaijou[n].inv();
		
		kaijou_.push_front(b);
		for(int i=1;i<=n;i++){
			int k=n+1-i;
			kaijou_.push_front(kaijou_[0]*k);
		}
	}
	
	mint combination(int n,int r){
		if(r>n)return 0;
		mint a = kaijou[n]*kaijou_[r];
		a *= kaijou_[n-r];
		return a;
	}
	
	mint junretsu(int a,int b){
		mint x = kaijou_[a]*kaijou_[b];
		x *= kaijou[a+b];
		return x;
	}
	
	mint catalan(int n){
		return combination(2*n,n)/(n+1);
	}
	
};

int main(){
	
	
	
	combi C(1000000);
	
	int n,s;
	cin>>n>>s;
	queue<A> Q;
	
	rep(i,n){
		int p;
		cin>>p;
		mint t = p;
		t /= s;
		A temp;
		rep(j,2)temp[j] = vector<mint>(2,1);
		temp[0][1] = t;
		temp[1][1] = t*t;
		temp[1][0] = 0;
		Q.push(temp);
	}
	while(Q.size()>1){
		auto x = Q.front();
		Q.pop();
		auto y = Q.front();
		Q.pop();
		A z;
		z[0] = convolution(x[0],y[0]);
		auto z0 = convolution(x[0],y[1]);
		auto z1 = convolution(x[1],y[0]);
		if(z0.size()>z1.size())swap(z0,z1);
		rep(j,z0.size())z1[j] += z0[j];
		z[1] = z1;
		Q.push(z);
	}
	
	mint ans = 0;
	auto z = Q.front();
	rep(i,z[1].size()){
		if(i==0)continue;
		mint t = z[1][i];
		t *= C.kaijou[i];
		t *= i+1;
		ans += t;
	}
	
	cout<<ans.val()<<endl;
	
	return 0;
}