MOD = 998244353

N = int(input())
S = input()

if '1' not in S:
  print(0)
  exit()

ans = 1
lst = S.find('1')
for i in range(lst + 1, N):
  if S[i] == '1':
    ans *= i - lst + 1
    ans %= MOD
    lst = i

print(ans)