import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

from collections import deque

n=II()
a=list(map(int,SI()))

b=1
tot=pow(2,n-1,md)
ans=0
for k in range(n):
    s = t = 1
    q = deque()
    q.append(1)
    for i in range(n):
        if len(q)>k:t-=q.popleft()
        if i-k>=0 and a[i-k]:
            q.append(t)
        else:
            q.append(s)
        s+=q[-1]
        t+=q[-1]
        s%=md
        t%=md
    ans+=(tot-q[-1])*b%md
    ans%=md
    b=b*2%md
print(ans)