#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
using ll = long long;

#include<atcoder/modint>
using mint = atcoder::modint998244353;


int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    ll n,k;
    cin>>n>>k;
    vector<ll> a(n);
    for(int i = 0;i<n;i++) cin>>a[i];
    ll sum = 0;
    for(int i = 0;i<n;i++) sum += a[i];
    vector<vector<mint>> dp(n+1,vector<mint>(3,0));
    dp[n][1] = 1;

    for(int i = n-1;i>=0;i--){
        sum -= a[i];
        if(sum==a[i]) {
            mint b = mint(a[i]-(-k));
            dp[i][2] += b * dp[i+1][1];
            dp[i][0] += dp[i+1][1];
            dp[i][0] += mint(a[i]-(-k)+1) * dp[i+1][0];
            dp[i][2] += mint(a[i]-(-k)+1) * dp[i+1][2];
        }else if(sum==a[i]+1){
            mint b = mint(a[i]-(-k));
            dp[i][2] += b * dp[i+1][1];
            dp[i][1] += dp[i+1][1];
            dp[i][0] += mint(a[i]-(-k)+1) * dp[i+1][0];
            dp[i][2] += mint(a[i]-(-k)+1) * dp[i+1][2];
        }else{
            mint b = mint(a[i]-(-k));
            dp[i][2] += b * dp[i+1][1];
            dp[i][1] += dp[i+1][1];
            dp[i][1] += mint(a[i]-(-k)+1) * dp[i+1][0];
            dp[i][2] += mint(a[i]-(-k)+1) * dp[i+1][2];
        }
    }

    mint ans = 1;
    for(int i = 0;i<n;i++) ans *= (a[i]-(-k)+1);
    ans -= dp[0][2];
    cout<<ans.val()<<endl;
    ans = dp[0][0] + dp[0][1];
    //cout<<ans.val()<<endl;
}