MOD = 998244353

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

pos_1 = []
for i, c in enumerate(S):
  if c == '1':
    pos_1.append(i)

ans = int(bool(pos_1))
for j in range(len(pos_1)-1):
  ans *= pos_1[j+1] - pos_1[j] + 1
  ans %= MOD

print(ans)