from itertools import groupby
N=int(input())
q=input()
r=[]
for a,b in groupby(q):
	r.append(len(list(b)))
if q[0]=="1":
	r=r[1:]
if q[-1]=="0":
	r=r[:-1]
c=1
for a in range(0,len(r),2):
	c*=r[a]+r[a+1]+1

print(c%998244353)