MOD = 998244353
N = int(input())
S = list(input())
ans = 0
f = 0

for s in S:
    if f == 0:
        if s == "1":
            f = 1
            cnt = 1
            ans = 1
    elif f == 1:
        if s == "0":
            cnt += 1
        else:
            ans *= (cnt + 1)
            ans %= MOD
            cnt = 1
print(ans)