A = [int(input()) for _ in range(5)][::-1]

lst = [1, 1]
for _ in range(100):
    lst.append(lst[-1] + lst[-2])

for i in range(5, -1, -1):
    B = A[:i]
    for j in range(i, 102):
        if lst[j-i:j] == B:
            print(i)
            exit()