N, M = map(int, input().split())
fib = [0, 1, 1]
for _ in range(80):
    fib.append(fib[-1] + fib[-2])


diff = fib[N] - M
ans = 0
for i in range(3, N+1):
    d = fib[N-i+1]
    if d <= diff:
        diff -= d
        ans += 1

if diff:
    print(-1)
else:
    print(ans)