mod = 998244353
n = int(input())
A = list(map(int,input().split()))
s = 0
for a in A:
    if a == 1:
        s += 1
    else:
        s += 1+s%2
ans = (1-pow(pow(-3,mod-2,mod),s,mod))*(mod+1)//2%mod
print(ans)