There are n beautiful skyscrapers in New York, the height of the i-th one is hi. Today some villains have set on fire first n−1 of them, and now the only safety building is n-th skyscraper.
Let's call a jump from i-th skyscraper to j-th (i<j) discrete, if all skyscrapers between are strictly lower or higher than both of them. Formally, jump is discrete, if i<j and one of the following conditions satisfied:
At the moment, Vasya is staying on the first skyscraper and wants to live a little longer, so his goal is to reach n-th skyscraper with minimal count of discrete jumps. Help him with calcualting this number.
The first line contains a single integer n (2≤n≤3⋅105) — total amount of skyscrapers.
The second line contains n integers h1,h2,…,hn (1≤hi≤109) — heights of skyscrapers.
Print single number k — minimal amount of discrete jumps. We can show that an answer always exists.
5 1 3145
4 4 224
2 1 1
5 100 11001100
In the first testcase, Vasya can jump in the following way: 1→2→4→5.
In the second and third testcases, we can reach last skyscraper in one jump.
Sequence of jumps in the fourth testcase: 1→3→5.
首先，要想明白这道题应该从何入手。这道题给人的第一感觉可能是 dp，却又不是简单的 dp。
进一步考虑，如何确定位置 j 的 dp 值呢？跳到位置 j 的上一个位置 i 应该满足如下条件之一：