import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

*A, = map(int,read().split())

A.reverse()

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

answer = 0
for n in range(1,6):
    seq = A[:n]
    for j in range(90):
        if seq == F[j:j+n]:
            answer = n

print(answer)