N=int(input())
S=list(map(int,list(input())))
if sum(S):
    idx=[]
    for i in range(N):
        if S[i]:
            idx.append(i)
    mod=998244353
    ans=1
    for l,r in zip(idx,idx[1:]):
        ans*=r-l+1
        ans%=mod
else:
    ans=0
print(ans)