N, M = map(int, input().split())
fib = [0, 1, 1]
for i in range(N - 2):
    fib.append(fib[-1] + fib[-2])
diff = fib[N] - M
if diff < 0:
    print(-1)
elif diff == 0:
    print(0)
else:
    cnt = 0
    for i in range(N-2, 0, -1):
        if fib[i] <= diff:
            diff -= fib[i]
            cnt += 1
    if diff == 0:
        print(cnt)
    else:
        print(-1)