m = 998244353
n, m_val = map(int, input().split())
a, b = 1, 1
for i in range(n):
    a = a * (n + m_val - i) % m
    b = b * (i + 1) % m
cur_a = [a, 0]
r = [cur_a]
for i in range(1, 5001):
    nxt_a = []
    for j in range(i + 1):
        t1 = cur_a[j - 1] * (i - j) * (n + m_val + j) % m if j > 0 else 0
        t2 = cur_a[j] * (j + 1) * (m_val + j - i + 1) % m if j < len(cur_a) else 0
        nxt_a.append((t1 + t2) % m)
    nxt_a.append(0)
    cur_a = nxt_a
    sm = sum(cur_a[:-1]) % m
    b = b * (n + i) % m
    r.append((sm * pow(b, -1, m)) % m)
print(sum(r[int(i)] for i in input().split()) % m)