SOJ.Opening Ceremony

1003. Opening Ceremony

时间限制：1秒    内存限制：256兆

题目描述

For the grand opening of the algorithmic games in NlogNsglow, a row of tower blocks is set to be demolished in a grand demonstration of renewal. Originally the plan was to accomplish this with controlled explosions, one for each tower block, but time constraints
now require a hastier solution.

To help you remove the blocks more rapidly you have been given the use of a Universal Kinetic / Incandescent Energy Particle Cannon (UKIEPC). On a single charge, this cutting-edge contraption can remove either all of the floors in a single tower block, or
all the x-th floors in all the blocks simultaneously, for user’s choice of the floor number x. In the latter case, the blocks that are less than x floors high are left untouched, while for blocks having more than x floors, all the floors above the removed
x-th one fall down by one level.

Given the number of floors of all towers, output the minimum number of charges needed to eliminate all floors of all blocks.

输入格式

The first line of input contains the number of blocks n, where 2 &#20;<= n <=&#20; 100 000. The second line contains n consecutive block heights hi for i = 1, 2, ..., n, where 1 <=&#20; hi <=&#20; 1 000 000.

输出格式

Output one line containing one integer: the minimum number of charges needed to tear down all the blocks.

样例输入

将样例输入复制到剪贴板

样例一：
6
2 1 8 8 2 3
样例二：
5
1 1 1 1 10

样例输出

样例一：
5
样例二：
2

Problem Source: 2015年每周一赛第四场