mod = 998244353
n = int(input())
s = list(map(int,input()))
# 主客転倒
r = 1
ans = 0
for i in range(1, n+1):
	dp0 = [0] * (n+1)
	dp1 = [0] * (n+1)
	dp0[0] = 1
	dp0s = [0] * (n+1)
	dp1s = [0] * (n+1)
	dp0s[0] = 1
	# j-i 以下から.
	for j in range(n):
		if j-i+1 >= 0:
			dp0[j+1] -= dp0s[j+1-i]
			dp1[j+1] -= dp1s[j+1-i]
			if s[j-i+1] == 0:
				dp0[j+1] += dp0s[j+1-i]
				dp1[j+1] += dp1s[j+1-i]
			else:
				dp1[j+1] += dp0s[j+1-i] + dp1s[j+1-i]
		dp0[j+1] += dp0s[j]
		dp1[j+1] += dp1s[j]
		dp0[j+1] %= mod
		dp1[j+1] %= mod
		dp0s[j+1] += dp0[j+1] + dp0s[j]
		dp1s[j+1] += dp1[j+1] + dp1s[j]
		dp0s[j+1] %= mod
		dp1s[j+1] %= mod
	#print(dp1[n])
	ans += dp1[n] * r
	ans %= mod
	r *= 2
	r %= mod
print(ans)