# coding: utf-8
import numpy as np
N, S = list(map(int, input().split()))
A = [0]+list(map(int, input().split()))

dt = np.array([[0 for _ in range(S+1)] for x in range(N+1)])

for n in range(1, N+1):
  if A[n] <= S:
    dt[n,A[n]] += n
    dt[n, A[n]+1:] += dt[n-1,1:S-A[n]+1] - dt[n-2,1:S-A[n]+1]
  dt[n,:] += dt[n-1,:] * 2 - dt[n-2,:]

print(dt[N,S] % 998244353)