import sys, time, random
from collections import deque, Counter, defaultdict
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353

n = ii()

s = input()

if '1' not in s:
    print(0)
else:
    bef = -1
    ans = 1
    for i in range(n):
        if s[i] == '1':
            if bef == -1:
                bef = i
            else:
                ans *= (i - bef + 1)
                ans %= mod
                bef = i
    print(ans)