# -*- coding: utf-8 -*-

N=int(input())
S=input()
MOD=998244353

ans=0
t=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)