MOD = 998244353
N = int(input())
C = list(map(int, input().split()))
if C[0] >= 0:
    ans = 1
    for i in range(N - 1):
        ans *= 2
        ans %= MOD
elif C[-1] <= 0:
    ans = 1
    for i in range(N - 1):
        ans *= 2
        ans %= MOD
else:
    ans = 2
    for i in range(N):
        if i == 0:
            pass
        elif i == N - 1:
            pass
        elif C[i] == 0:
            ans *= 3
        else:
            ans *= 2
        ans %= MOD
print(ans)