抓住那头奶牛

题目描述

Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. 农夫约翰已经获悉逃跑的牛的位置，想立刻抓住它。

He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. Farmer John has two modes of transportation: walking and teleporting. 农夫约翰位于数轴上的点 N（0 ≤ N ≤ 100,000）处，奶牛位于同一数轴的点 K（0 ≤ K ≤ 100,000）处，他有两种移动方式：步行和闪移。

• Walking: FJ can move from any point X to the points X - 1 or X + 1 in a single minute 步行：每分钟可以从点 X 移动到 X - 1 或 X + 1
• Teleporting: FJ can move from any point X to the point 2 * X in a single minute. 闪移：每分钟可以从点 X 移动到 2 * X

If the cow, unaware of its pursuit, does not move at all, how long does it take for Farmer John to retrieve it? 假设奶牛始终静止不动，请求出 Farmer John 抓住奶牛所需的最少时间（单位：分钟）。

输入描述

第一行：两个空格分隔的整数 N 和 K

输出描述

第一行：Farmer John 抓住奶牛所需的最少分钟数

输入样例

5 17

输出样例

4

提示

最快路径为 5 → 10 → 9 → 18 → 17，共耗时4分钟。 注意移动时下标防止越界，允许往回走。