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

ans = 0
f = [0, 1, 1, 2, 3]
for i in range(100):
    if f[0] == A[0]:
        ans = 1
        for i in range(1, 5):
            if f[i] == A[i]:
                ans += 1
            else:
                break
        break
    elif f[0] > A[0]:
        break
    f[0:4] = f[1:5]
    f[4] += f[2]

print(ans)