def fibo(n):
    f = [0, 1]
    for i in range(n-1):
        f.append(f[-1] + f[-2])
    return f


def split(n, f):
    f = f[::-1]
    s = []
    for m in f[2:]:
        if m <= n:
            s.append(m)
            n -= m
        if n == 0:
            return s


def solve(n, m):
    f = fibo(n)
    d = f[-1] - m
    if d < 0:
        return -1
    elif d == 0:
        return 0
    else:
        return len(split(d, f))


n, m = map(int, input().strip().split(' '))
print(solve(n, m))