Roadside Trees (Simplified Edition)

题意翻译

大街上有 $n$ 棵树，每棵树的树顶都有一个坚果。一只松鼠在第一棵树的最底端，这只松鼠可以在一秒钟完成以下几个动作。 - 往下或往上爬一米。 - 如果松鼠在树顶，就可以吃掉树顶的坚果。 - 从第 $i$ 棵树跳到第 $i+1$ 棵树。（这时松鼠的高度不变，如果第 $i$ 棵比第 $i+1$ 棵高，就不可以执行此动作） 这只松鼠想要吃掉所有的坚果，请求出吃掉所有坚果一共需要用多少秒。

题目描述

Squirrel Liss loves nuts. There are $ n $ trees (numbered $ 1 $ to $ n $ from west to east) along a street and there is a delicious nut on the top of each tree. The height of the tree $ i $ is $ h_{i} $ . Liss wants to eat all nuts. Now Liss is on the root of the tree with the number $ 1 $ . In one second Liss can perform one of the following actions: - Walk up or down one unit on a tree. - Eat a nut on the top of the current tree. - Jump to the next tree. In this action the height of Liss doesn't change. More formally, when Liss is at height $ h $ of the tree $ i $ ( $ 1<=i<=n-1 $ ), she jumps to height $ h $ of the tree $ i+1 $ . This action can't be performed if $ h&gt;h_{i+1} $ . Compute the minimal time (in seconds) required to eat all nuts.

输入输出格式

输入格式

The first line contains an integer $ n $ ( $ 1<=n<=10^{5} $ ) — the number of trees. Next $ n $ lines contains the height of trees: $ i $ -th line contains an integer $ h_{i} $ ( $ 1<=h_{i}<=10^{4} $ ) — the height of the tree with the number $ i $ .

输出格式

Print a single integer — the minimal time required to eat all nuts in seconds.

输入输出样例

输入样例 #1

2
1
2

输出样例 #1

5

输入样例 #2

5
2
1
2
1
1

输出样例 #2

14