subseq.py

MOD = 998244353


def _find_range(a: list, b: list):
    if len(b) == 1:
        return int(b[0] == min(a))
    for x in range(len(a) - 1, len(a) - len(b) - 2, -1):
        if a[x] < b[-1]:
            return 0
        if b[-1] == a[x]:
            j = x
            break
    else:
        return 0
    bi = len(b) - 1
    count = 0
    mult = 1
    while j >= 0 and bi > 0:
        if a[j] < b[bi]:
            mult = count * mult
            count = 0
            bi -= 1
            while j >= 0:
                if a[j] < b[bi]:
                    return 0
                if a[j] == b[bi]:
                    break
                j -= 1
            else:
                return 0
        j -= 1
        count += 1
    mult = mult * count
    if bi > 1:
        return 0
    if min(a[: j + 2]) == b[0]:
        return mult % MOD
    else:
        return 0


def count_permutations(a: list, b: list):
    return _find_range(a, b)


if __name__ == "__main__":
    (n, m) = tuple([int(x) for x in input().rstrip().split()])
    a = list([int(x) for x in input().rstrip().split()])
    b = list([int(x) for x in input().rstrip().split()])
    result = count_permutations(a, b)
    print(result)