MOD = 998244353

n = int(input())
s = input()

ans = 0
dp = [0] * (n + 1)
for k in range(n):
  dp[0] = 1
  for i in range(n):
    if i - k < 0 or s[i - k] == '0':
      dp[i + 1] = 2 * dp[i] % MOD
    else:
      dp[i + 1] = (2 * dp[i] - dp[i - k]) % MOD
  ans += (pow(2, n - 1, MOD) - (dp[n] - dp[n - 1])) * pow(2, k, MOD)
  ans %= MOD
print(ans)