F=[1,1,2,3]
while F[-1]<=10**15:
    F.append(F[-1]+F[-2])
ANS=0
A=[int(input()) for i in range(5)][::-1]

for j in range(6):
    for k in range(len(F)-j):
        if A[:j]==F[k:k+j]:
            ANS=max(ANS,j)

print(ANS)