N = int(input())
A = input()


def solve(s):
    s = s.lstrip("1").rstrip("0")
    f0 = True
    count = 0
    sum = 1
    for i in range(len(s)):
        if s[i] == "1":
            if f0:
                f0 = False
                count += 1
            else:
                count += 1
        else:
            if f0:
                count += 1
            else:
                f0 = True
                sum *= count + 1
                count = 1
    sum *= count + 1
    return sum


print(solve(A) % 998244353)