#include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, k, n) for (int i = k; i < (int)(n); i++)
#define repd(i, n) for (int i = n-1; i >= 0; i--)
#define rrepd(i, k, n) for (int i = n-1; i >= (int)(k); i--)
#define all(x) (x).begin(),(x).end()
#define chmax(x,y) x=max(x,y)
#define chmin(x,y) x=min(x,y)
#define F first //pairの一つ目の要素
#define S second //pairの二つ目の要素
#define PB push_back //挿入
#define MP make_pair //pairのコンストラクタ
//V,Pは大文字i,l,bは小文字
using ll = long long;
using Vi = vector<int>;
using VVi = vector<Vi>;
using Vl = vector<ll>;
using VVl = vector<Vl>;
using Vb = vector<bool>;
using VVb = vector<Vb>;
using P = pair<int,int>;
using Pl = pair<ll, ll>;
using Vs = vector<string>;
const ll mod = 998244353;

struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
const ll inf = 1000000000000000000;//10の12乗
#define yn {puts("Yes");}else{puts("No");}
#define dame { puts("-1"); return 0;}

int main() {
  ll n,k;
  cin >> n >> k;
  mint sum=0;
  rep(i,n){
      ll x;
      cin >> x;
      sum+=x;
  }
  mint num=(k+1)%mod;
  num*=(k%mod);
  num/=2;
  num+=1;
  sum*=num.x;
  cout << sum.x << endl;
}