N,M = map(int, input().split())
a = [0]*5001
nSk = [[0]*5005 for i in range(5005)]
nSk[0][0] = 1
for i in range(1,5005):
  for j in range(1, 5005):
    nSk[i][j] = nSk[i-1][j-1] + j*nSk[i-1][j]
    nSk[i][j] %= 998244353
nCr = [0]*5001
fact = [1]*5001
temp = 1
for i in range(1,N+1):
  temp *= (M+i)*pow(i,-1,998244353)%998244353
  temp %= 998244353
for i in range(5001):
  nCr[i] = temp
  temp *= (M+N+i+1)*pow(N+i+1,-1,998244353)%998244353
  temp %= 998244353
for i in range(1,5001):
  fact[i] = i*fact[i-1]%998244353
for k in range(5001):
  for j in range(5001):
    a[k] += nCr[j]*(1 if (k+j)%2 == 0 else 998244352)%998244353*fact[j]%998244353*nSk[k+1][j+1]%998244353
    if a[k] >= 998244353:
      a[k] -= 998244353
ans = 0
for k in list(map(int, input().split())):
  ans += a[k]
  if ans >= 998244353:
    ans -= 998244353
print(ans)