import sys
input = sys.stdin.readline
mod = 998244353

N = int(input())
S = input().rstrip('\n')

ans = 0
for k in range(1, N + 1):
    dp = [0] * N
    cs = [0]
    for i in range(N):
        if i + 1 - k < 0:
            dp[i] = (cs[-1] + 1) % mod
        else:
            if S[i + 1 - k] == "0":
                dp[i] = (cs[-1] + 1) % mod
            else:
                dp[i] = (cs[-1] - cs[-k]) % mod
        cs.append((cs[-1] + dp[i]) % mod)
    num = (pow(2, N - 1, mod) - dp[-1]) % mod
    ans = (ans + (num * pow(2, k - 1, mod)) % mod) % mod
    #print(k, num, dp)
print(ans)