MOD = 998244353
N = int(input())
S = list(map(int, list(input())))
M = [0] * (N + 1)
E = [[0] * (N) for _ in range(N)]
SumE = [0] * N
M[0] = 1
M[1] = 1
now = 1
for i in range(N):
    s = S[N - i - 1]
    E[N - i - 1] = SumE[:]
    for j in range(i + 1):
        SumE[j] += SumE[j]
        SumE[j] %= MOD
        if s == 1:
            tmp = M[i - j] - E[N - i + j - 1][j]
            E[N - i + j - 1][j] = M[i - j]
            SumE[j] += tmp
            SumE[j] %= MOD
    if i > 0:
        M[i + 1] = M[i] * 2
        M[i + 1] %= MOD
    #print(i, M, SumE)
    #for k in range(N):
    #    print(E[k])
ans = 0
tmp = 1
for i in range(N):
    ans += tmp * SumE[i]
    ans %= MOD
    tmp *= 2
    tmp %= MOD
print(ans)