Проверить, чередуются ли в массиве положительные и отрицательные числа

N = int(input("N:"))
a = [1 for i in range(N)]
for i in range(N):
    a.append(int(input(" = ")))
 
Temp=(a[0]>0)
i = 1
 
while ((i<N) and (Temp!=(a[i]>0))) and (a[i]*a[i+1])<0:
    i+=1
    
if i>N:
    print('0')
else:
    print('', i,'элемент')

array_len = int(input("N: "))
array = []
for i in range(array_len):
    array.append(int(input(str(i) + " = ")))
 
k=0
for i in range(len(array) - 1):
    if array[i]<0 and array[i+1]>=0:
        continue
    elif array[i]>=0 and array[i+1]<0:
        continue
    else:
        k=i+1
        break
print(k)

array_len = int(input("N: "))
array = []
for i in range(array_len):
    array.append(int(input(str(i) + " = ")))
 
k=0
for i in range(len(array) - 1):
    if array[i]<0 and array[i+1]>=0:
        continue
    elif array[i]>=0 and array[i+1]<0:
        continue
    else:
        k=i+1
        break
print(k)

N = int(input("N:"))
a = []
for i in range(N):
    a.append(int(input()))
prev = a[0]
res = True
for i,x in enumerate(a[1::]):
    if (prev >= 0 and x >= 0) or (prev <= 0 and x <= 0):
        res = False
        break
    prev = x
if (res):
    print(0)
else:
    print(i)

from itertools import tee, takewhile
 
 
def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b)
 
 
def diff_sign(pair):
    a, b = pair
    return (a>=0 and b<0) or (a<0 and b>=0)
 
 
def alternated(seq):
    l = sum(1 for i in takewhile(diff_sign, pairwise(seq)))
    if l == len(seq)-1:
        return 0
    else:
        return seq[l+1]
 
print(alternated([1,-3, -4, -5, -6]))

k=i+2