ZFTSH Programming Elements Task 5

def play(i, j):
    global A
    ans = 0
    if all((A[k] + A[k+2]) / 2 == A[k+1] for k in range(i, j-2)):
        if ans < j - i:
            ans = j - i
    elif all(A[k] * A[k+2] == A[k+1]**2 for k in range(i, j-2)):
        if ans < j - i:
            ans = j - i
    return ans

A = []
x = int(input())
while x != 0:
    A.append(x)
    x = int(input())

itog = []
for i in range(len(A)):
    for j in range(i+1, len(A)):
        res = play(i, j)
        itog.append(res)

print(max(itog))