N = int(input())
C = list(map(int,input().split()))
MOD = 998244353
if N==1:
    ans = 1
else:
    k = 0
    for i in range(N):
        if C[i]<0:
            k += 1
        else:break
    if 0 not in C:
        ans = pow(2,N-1,MOD)
    elif k==0 or k==N-1:
        ans = pow(2,N-1,MOD)
    else:
        ans = (3*pow(2,N-2,MOD))%MOD
print(ans)