import re

n = int(input())
a = input()
result = 0

blocks = re.findall('0+|1+', a)

def calc(array):
    if len(array) == 1:
        return 1
    pre = 0
    for i in range(len(array)):
        if i == 0:
            if "1" in array[i]:
                continue
        elif i == len(array)-1:
            if "0" in array[i]:
                continue
        else:
            array1 = array[:i-1] + [array[i-1] + array[i-1][0]*len(array[i]) + array[i+1]] + array[i+2:]
            pre += len(array[i]) + calc(array1)
    return pre

print(calc(blocks)%998244353)