#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
typedef long long ll;
const int INF = 1<<30;
const ll INFLL = 1LL<<60;
const ll MOD = 998244353;
const double INFD = 1.0E18;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, -1, 0, 1};
//const int dx[8] = {1, 1, 0, -1, -1, -1, 0, 1};
//const int dy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
using Pair = pair<ll, ll>;
using Graph = vector<vector<pair<int, int>>>;
using mint = atcoder::modint998244353;


int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
    ll n, k; cin >> n >> k;
    vector<ll> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    mint ans = 1;
    auto f = [&](int x) -> mint{
        //すべてxより小さくなる確率
        mint ret = 1;
        for (int i = 0; i < n; i++){
            if (a[i] < x) continue;
            ret *= (x - 1) * mint(a[i]).inv();
        }
        return ret;
    };
    
    cout << (f(k + 1) - f(k)).val() << endl;
    
    return 0;
}