from itertools import*
n=int(input())
a=input()
M=998244353
r=[(k,len([*v]))for k,v in groupby(a)]
ans=1
for(k1,v1),(k2,v2)in zip(r,r[1:]):
  if k1+k2=='01':
    ans+=ans*(v1+v2)
    ans%=M
print(ans)