#include <bits/stdc++.h>
using namespace std;
using ll=long long;
const ll ILL=2167167167167167167;
const int INF=2100000000;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> int LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> int UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(b<a){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=false){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
template<class T> T square(T a){return a * a;}

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

void solve();
// CITRUS CURIO CITY / FREDERIC
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    int N, M;
    cin >> N >> M;
    mint ans = 0;
    vector<ll> A(N);
    for (auto &a : A){
        cin >> a;
        ans += M - a;
    }
    ans += M;
    rep(i, 0, N - 1) ans *= M;

    vector<mint> dp(3);
    dp[0] = min(A[0], A[1]);
    dp[1] = abs(A[0] - A[1]);
    dp[2] = M - max(A[0], A[1]);
    A.push_back(M);
    rep(i, 0, N - 1){
        vector<ll> tmp = {0, A[i], A[i + 1], A[i + 2], M};
        vector<mint> n_dp(3);
        So(tmp);
        rep(a, 0, 3) rep(b, 0, 4){
            mint c = tmp[b + 1] - tmp[b];
            if (c.val() == 0) continue;
            if (A[i] < A[i + 1] && a != 1 && A[i] <= tmp[b] && tmp[b] < A[i + 1]) {
                continue;
            }
            if (A[i] > A[i + 1] && (A[i] <= tmp[b] || tmp[b] < A[i + 1]) && a == 1){
                continue;
            }
            int d = (A[i + 1] <= tmp[b]) + (A[i + 2] <= tmp[b]);
            n_dp[d] += c * dp[a];
        }
        swap(n_dp, dp);
    }
    /*vector<mint> dp(M, 1);
    rep(i, 0, N - 1){
        vector<mint> n_dp(M);
        rep(a, 0, M) rep(b, 0, M){
            if (A[i] < A[i + 1]){
                if (a >= A[i + 1] && A[i + 1] > b && b >= A[i]) continue;
                if (A[i + 1] > b && b >= A[i] && A[i] > a) continue;
            }
            if (A[i] > A[i + 1]){
                if (b >= A[i] && A[i] > a && a >= A[i + 1]) continue;
                if (A[i] > a && a >= A[i + 1] && A[i + 1] > b) continue;
            }
            n_dp[b] += dp[a];
        }
        swap(n_dp, dp);
    }*/
    ans -= vec_sum(dp);
    cout << ans.val() << "\n";
}
// A[i] < A[i + 1] の時、
// B[i] >= A[i + 1] > B[i + 1] >= A[i] ならば、 + 1
// A[i + 1] > B[i + 1] >= A[i] > B[i] でも + 1