A = [int(input()) for i in range(5)]
A.reverse()

dp = [1, 1]
for i in range(10**5):
    x = dp[-2]+dp[-1]
    if x > 10**15:
        break
    dp.append(x)

ans = 0
for i in range(len(dp)-4):
    B = dp[i:i+5]
    for j in range(5):
        if A[j] != B[j]:
            break
        else:
            ans = max(ans, j+1)
print(ans)