## https://yukicoder.me/problems/no/2279

MOD = 998244353



def main():
    N = int(input())
    S = input()

    dp = [[0] * N for _ in range(N)]
    cum_dp = [[0] * N for _ in range(N)]

    dp[0][0] = int(S[0])
    cum_dp[0][0] = int(S[0])

    for i in range(1, N):

        for j in reversed(range(i)):
            if int(S[j + 1]) == 1:
                dp[i][i - 1 - j] = pow(2, j + 1, MOD)
            else:
                dp[i][i - 1 - j] = cum_dp[j][i - 1 - j]
            
            dp[i][i - 1 - j] += (cum_dp[i - 1][i - 1 - j] - cum_dp[j][i - 1 - j]) % MOD
            dp[i][i - 1 - j] %= MOD
        
        dp[i][i] = int(S[0])

        for j in range(N):
            cum_dp[i][j] = (dp[i][j] + cum_dp[i - 1][j]) % MOD
    answer = 0
    for i in range(N):
        weight = pow(2, i, MOD)
        answer += (weight * dp[-1][i]) % MOD
        answer %= MOD
    print(answer)








if __name__ == "__main__":
    main()