import sys

def main():
    data = sys.stdin.buffer.read().split()
    N = int(data[0])
    A = data[1].decode()
    MOD = 998244353

    l = 0
    while l < N and A[l] == '1':
        l += 1
    r = N - 1
    while r >= 0 and A[r] == '0':
        r -= 1

    if l > r:
        R0 = 1
    else:
        R0 = 1
        i = l
        while i <= r:
            j = i
            while j <= r and A[j] == '0':
                j += 1
            k = j
            while k <= r and A[k] == '1':
                k += 1
            R0 = R0 * (k - i + 1) % MOD
            i = k

    print(R0)

main()