import re

N = int(input())
a = input()
result = 1

blocks = re.findall('0+|1+', a)
if len(blocks) >0:
    if "1" in blocks[0]:
        ##n = n - len(blocks[0])
        blocks = blocks[1:]
if len(blocks) >0:
    if "0" in blocks[-1]:
        ##n = n - len(blocks[-1])
        blocks = blocks[:-1]


blocks = [len(x) for x in blocks]


if len(blocks) >0:
    for i in range(int(len(blocks)/2)):
        index1 = 2*i
        index2 = 2*i + 1
        result = result*(blocks[index1] + blocks[index2] + 1)
 

print(result%998244353)