import sys
input = lambda: sys.stdin.readline().strip()

def Map():
  return list(map(int,input().split()))

N = int(input())
S = input()
mod = 998244353

ans = 1
f = 0
c = 0
for i in range(N):
  if f:
    if S[i] == '1':
      ans *= (c+1)
      ans %= mod
      c = 1
    else:
      c += 1
  else:
    if S[i] == '1':
      f = 1
      c = 1
if f == 0:
  ans = 0
print(ans)