import re

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

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):
    global result
    n = sum(arr)
    k = len(arr)
    if k == 2:
        result += n
        result = result%998244353
        return 
    result += n
    result = result%998244353
    for i in range(k):
        calc(merge(arr, i))
    return


calc(blocks)
print(result%998244353)