I,R=input,range
N=int(I())
M=R(N)
A=[[0]*N for i in R(N+1)]
B=[0]*N
S=I()
P=998244353
for i in R(1,N+1):
	s=S[N-i]>"0"
	for j in R(i):
		B[j]+=(S[N-i]>"0")*(pow(2,max(0,i-j-1-1),P)-A[i-j-1][j])
		A[i][j]=B[j]%P
print(sum(pow(2,j,P)*A[N][j]for j in M)%P)