import re

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

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


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


def merge(arr, i):
    if i == 0:
        return arr[2:]
    if i == len(arr) - 1:
        return arr[:-2]
    arr[i - 1] += arr.pop(i) + arr.pop(i)
    return arr

def calc(arr):
    n = sum(arr)
    k = len(arr)
    if k == 2:
        return n
    pre = n
    for i in range(k):
        pre += calc(merge(arr, i))
    return pre



print(calc(blocks)%998244353)