N=int(input())
A=list(map(int,input().split()))
DP=[[0]*5 for i in range(N+1)]
mod=998244353
DP[0][1]=1
for i in range(N):
  DP[i+1][1]=pow(2,i,mod)
for i in range(N):
  for j in range(-2,3):
    if abs(A[i]*j)>3:
      continue
    DP[i+1][j*A[i]]=(DP[i+1][j*A[i]]+DP[i][j])%mod
print((sum(DP[i][-2]*pow(2,N-i-1,mod) for i in range(N))+DP[N][-2])*pow(pow(2,mod-2,mod),N-1,mod)%mod)