N=int(input())
A=list(map(int,input().split()))
sum=sum(A)
if sum==0 or sum==N:
    print(0)
    exit(0)
MOD=998244353
cnt=0
for i in range(N):
    if A[i]==0 and A[(i+1)%N]==1:cnt+=1
ans=cnt*pow(N,-1,MOD)%MOD
print(ans)