N = int(input())
S = input()
p = 998244353
dp = [0] * (N + 1)
dp[0] = 1
cum = [0] * (N + 1)
cum[1] = 1
j = -1
for i, s in enumerate(S):
    if s == "1":
        j = i
    if j == -1:
        cum[i + 1] += cum[i]
        cum[i + 1] %= p
        continue
    cum[i + 1] = (cum[i] + dp[i]) % p
    dp[i + 1] = cum[j + 1]

print(dp[N])
# print(dp)
# print(cum)