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 i in range(4):
    for j in range(i+1,6):
        for k in range(len(F)-(j-i)):
            if A[i:j]==F[k:k+j-i]:
                ANS=max(ANS,j-i)

print(ANS)