#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int MAXN = 3e3 + 5;
const int mod = 998244353;

int f[MAXN][MAXN];//use x numbers to get y
int gao(int x,int y)
{
	if(y>x) return 0;
	if(~f[x][y]) return f[x][y];
	if(!x) return f[x][y] = !y;
	if(!y) return f[x][y] = 0;
	return f[x][y] = (gao(x, y*2) + gao(x-1, y-1)) %mod;
}

int main(void)
{
	int n,d;
	scanf("%d%d",&n,&d);
	
	memset(f,-1,sizeof(f));
	printf("%d",gao(n,d));
	return 0;
}
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
using Graph= vector<vector<int>>; 
#define rep(i,n) for (ll i=0; i < (n); ++i)
#define rep2(i,n,m) for(ll i=n;i<=m;i++)
#define rep3(i,n,m) for(ll i=n;i>=m;i--)
#define pb push_back
#define eb emplace_back
#define ppb pop_back
#define fi first 
#define se second
#define mpa make_pair
const ll INF=1e18 ;
inline void chmax(ll& a,ll b){a=max(a,b);}
inline void chmin(ll& a,ll b){a=min(a,b);}
ll gcd(ll a, ll b) { return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}
#define set20 cout<<fixed<<setprecision(20) ;
// ミント
//int mod ; cin>>mod ;
const ll mod = 1e9+7 ;//924844033;  
  //  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;
  }
 
  // for prime mod
  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;}
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}
//昆布
struct combination {
  vector<mint> fact, ifact;
  combination(int n):fact(n+1),ifact(n+1) {
    assert(n < mod); //任意modではここ消す
    fact[0] = 1;
    for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n]*ifact[k]*ifact[n-k];
  }
  mint p(int n,int k){
    return fact[n]*ifact[n-k] ;
  }
  }  ;
 
mint modpow(ll a,ll b){
 if(b==0) return 1 ;
 mint c= modpow(a,b/2) ;
 if(b%2==1) return c*c*a ;
 else return c*c ;
}
 
mint komb(ll n,ll m){
  mint x=1 ;mint y=1 ;
  rep(i,m){
    x*= n-i ;
    y*= i+1 ;
  }
  return x/y ;
}
 
 
 map<ll,ll> factor(ll n){  //素因数とオーダーをマップで管理
  map <ll,ll> ord ;  
  for(ll i=2;i*i<=n;i++){
        if(n%i==0){
            int res=0;
            while(n%i==0){
                n/=i;
                res++;
            }
            ord[i]=res;
        }
    }
   if(n!=1) ord[n]++;
   return ord ;
 }


mint dp[100005][2] ;
mint sum[100005][2] ;

int main(){
  ll n ; cin>>n ;
  vector<ll> A(n) ;
  rep(i,n) cin>>A[i] ;
  dp[1][0]=1ll ;
  //dp[1][1] =1ll ;
  sum[1][0]=A[0] ;
  //sum[1][1]=A[0] ;
  rep(i,n-1){
    dp[2+i][0]=dp[1+i][0]+dp[1+i][1] ;
    dp[2+i][1]=dp[1+i][0] ;
    sum[2+i][0]=sum[1+i][0]+sum[1+i][1]+mint(A[i+1])*(dp[2+i][0]) ;
    sum[2+i][1]=sum[1+i][0]-mint(A[i+1])*(dp[2+i][1]) ;
  }

  mint ans=sum[n][0]+sum[n][1] ;
  cout<<ans<<endl ;
  return 0 ;
  }