n = int(input())
s = input().strip('0')
n = len(s)
if n == 0:
	exit(print(0))
ans = 1
now = 0
mod = 998244353
for i in s:
	if i == '0':
		now += 1
	else:
		ans = ans * (now + 2) % mod
		now = 0
print(ans * 499122177 % mod)