mod = 998244353

n = int(input())
s = input()

ans, t, = 0, 0

for i in range(n):
    if s[i] == "1":
        if ans == 0:
            ans = 1
        else:
            ans *= t + 2
            ans %= mod
        t = 0
    else:
        t += 1
print(ans)