import sys
sys.setrecursionlimit(5*10**5)
input = sys.stdin.readline
from collections import defaultdict, deque, Counter
from heapq import heappop, heappush
from bisect import bisect_left, bisect_right
from math import gcd

n = int(input())
s = input().rstrip()
dp = [0]*(n+1)
dp[0] = 1
last = -1
for i in range(1,n+1):
    if s[i-1] == "1":
        dp[i] += dp[i-1]
        last = i
    elif last != -1:
        dp[i] += dp[last-1]
    dp[i] += dp[i-1]
    dp[i] %= 998244353
print((dp[-1]-dp[-2])%998244353)