CF1070D.Garbage Disposal

Enough is enough. Too many times it happened that Vasya forgot to dispose of garbage and his apartment stank afterwards. Now he wants to create a garbage disposal plan and stick to it.

For each of next $n$ days Vasya knows $a_i$ — number of units of garbage he will produce on the $i$-th day. Each unit of garbage must be disposed of either on the day it was produced or on the next day. Vasya disposes of garbage by putting it inside a bag and dropping the bag into a garbage container. Each bag can contain up to $k$ units of garbage. It is allowed to compose and drop multiple bags into a garbage container in a single day.

Being economical, Vasya wants to use as few bags as possible. You are to compute the minimum number of bags Vasya needs to dispose of all of his garbage for the given $n$ days. No garbage should be left after the $n$-th day.

够了！维佳已经太多次忘记处理垃圾，导致公寓随后臭气熏天。现在他想制定一个垃圾处理计划并严格遵守。

对于接下来的 $n$ 天中的每一天，维佳都知道第 $i$ 天将产生 $a_i$ 单位的垃圾。每单位垃圾必须在产生的当天或第二天内处理完毕。维佳通过将垃圾装入袋子，再将袋子投入垃圾箱来处理垃圾。每个袋子最多可容纳 $k$ 单位垃圾。允许在同一天内准备并投入多个袋子到垃圾箱中。

出于节约考虑，维佳希望使用尽可能少的袋子。你需要计算维佳在给定的 $n$ 天内处理全部垃圾所需的最少袋子数量。第 $n$ 天之后不得残留任何垃圾。

The first line of the input contains two integers $n$ and $k$ ($1 \le n \le 2\cdot10^5, 1 \le k \le 10^9$) — number of days to consider and bag's capacity. The second line contains $n$ space separated integers $a_i$ ($0 \le a_i \le 10^9$) — the number of units of garbage produced on the $i$-th day.

输入的第一行包含两个整数 $n$ 和 $k$（$1 \le n \le 2\cdot10^5$，$1 \le k \le 10^9$）—— 分别表示需考虑的天数和垃圾袋的容量。
第二行包含 $n$ 个用空格分隔的整数 $a_i$（$0 \le a_i \le 10^9$）—— 表示第 $i$ 天产生的垃圾单位数量。

Output a single integer — the minimum number of bags Vasya needs to dispose of all garbage. Each unit of garbage should be disposed on the day it was produced or on the next day. No garbage can be left after the $n$-th day. In a day it is allowed to compose and drop multiple bags.

输出一个整数——Vasya 处理所有垃圾所需的最少袋子数量。每单位垃圾必须在产生的当天或第二天处理完毕，且不能有任何垃圾留到第 $n$ 天之后。每天可以制作并投放多个袋子。