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

ans = 0
C = pow(2, N - 1, MOD)

for k in range(N - 1, 0, -1):
    dp = [0] * N
    dp[0] = 1
    for i in range(N - 1):
        dp[i + 1] = dp[i] * 2
        j = i - k
        if j >= 0:
            if S[j] == '1':
                dp[i + 1] -= dp[j]
        dp[i + 1] %= MOD
    j = N - 1 - k
    if j >= 0:
        if S[j] == '1':
            dp[-1] -= dp[j]
    ans *= 2
    ans += C - dp[-1]
    ans %= MOD

ans *= 2
if S[-1] == '1':
    ans += C
else:
    cnt = S.count('0')
    ans += C - pow(2, cnt - 1, MOD)

ans %= MOD
print(ans)