"""
おもしろそう
0 ... 1 を自由にできるで必要十分？
"""

mod = 998244353

II = lambda : int(input())
MI = lambda : (int(_) for _ in input().split())

n = II()
a = "1" + input() + "0"
sp = []
for i in range(n+1):
    if a[i] == "1" and a[i+1] == "0":
        sp.append(i)

ans = 1
for i in range(len(sp) - 1):
    ans = ans * (sp[i+1] - sp[i] + 1) % mod
print(ans)