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

K = pow(2,N - 1,P)
ans = 0
for i in range(1,N + 1):
    dp = [0] * (N + 2)
    U = [0] * (N + 2)
    dp[0] = 1

    for j in range(N + 1):
        if j > 0:
            U [j] += U[j-1]
            U[j] %= P
            dp[j] = U[j]
        if i + j <= N and S[-(i+j)] == "1":
            U[i + j] -= dp[j]
        U[j + 1] += dp[j]
        U[j + 1] %= P
        #print(dp[j])
    last = U[-1]
    ans += pow(2,i-1,P) * (pow(2,N -1,P) - last) % P
print(ans % P)