mod = 998244353

N,M = map(int,input().split())
k = list(map(int,input().split()))
K = max(k)

cnt = [0 for i in range(K+1)]
for i in range(N):
    cnt[k[i]] += 1

COMB = [0 for j in range(K+2)]
comb = 1
for i in range(N-1):
    comb *= (M+N-1-i) * pow(i+1,mod-2,mod) % mod
    comb %= mod
COMB[0] = comb
for j in range(1,K+2):
    COMB[j] = COMB[j-1] * (M+N-1+j) * pow(N-1+j,mod-2,mod) % mod
    COMB[j] %= mod

tmp = [0] * (K+3)
tmp[-1] = 1

res = 0
for i in range(1,K+1):
    for j in range(-K-1,0):
        if not tmp[j]:
            continue
        tmp[j-1] = -j*tmp[j] % mod
        tmp[j] = 0
    for j in range(-K-1,0)[::-1]:
        if not tmp[j]:
            continue
        tmp[j+1] -= tmp[j]
        tmp[j+1] %= mod
    
    for j in range(-K-1,0):
        res += tmp[j] * (COMB[-j] * cnt[i] % mod) % mod
        res %= mod

print(res)