import sys
from collections import deque

N = int(input().strip())
A = input().strip()

dic = {A}
test = deque([A])
while test:
    target = test.popleft()
    
    for i in range(N - 1):
        if target[i:i+2] == "01":

            target_change1 = target[:i] + "1" + target[i+1:]
            if not(target_change1 in dic):
                dic.add(target_change1)
                test.append(target_change1)

            target_change0 = target[:i+1] + "0" + target[i+2:]
            if not(target_change0 in dic):
                dic.add(target_change0)
                test.append(target_change0)

modulo = len(dic) % 998244353
print(modulo)