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

pw = 1
ans = 0
tot = pow(2, N-1, P)
for k in range(N) :
    dp = [0] * (N+1)
    s = [0] * (N+1)
    dp[0] = 1
    for i in range(N) :
        s[i+1] = (s[i] + dp[i]) % P
        dp[i+1] = s[i+1]
        if i - k >= 0 and S[i-k] == '1' :
            dp[i+1] = (dp[i+1] - s[i-k+1] + P) % P
    ans = (ans + (tot - dp[N] + P) * pw) % P
    pw = 2 * pw % P
print(ans)