CF276C.Little Girl and Maximum Sum

The little girl loves the problems on array queries very much.

One day she came across a rather well-known problem: you've got an array of $n$ elements (the elements of the array are indexed starting from 1); also, there are $q$ queries, each one is defined by a pair of integers $l_i$, $r_i$ $(1 \le l_i \le r_i \le n)$. You need to find for each query the sum of elements of the array with indexes from $l_i$ to $r_i$, inclusive.

The little girl found the problem rather boring. She decided to reorder the array elements before replying to the queries in a way that makes the sum of query replies maximum possible. Your task is to find the value of this maximum sum.

这位小女孩非常喜爱有关数组查询的问题。

一天，她遇到了一个相当著名的问题：你有一个包含 $n$ 个元素的数组（数组元素的下标从 1 开始）；此外，还有 $q$ 个查询，每个查询由一对整数 $l_i$, $r_i$ $(1 \le l_i \le r_i \le n)$ 定义。对于每个查询，你需要计算数组中下标从 $l_i$ 到 $r_i$（含端点）的所有元素之和。

小女孩觉得这个问题相当枯燥。她决定在回答查询之前，对数组元素进行重排，使得所有查询结果之和达到最大可能值。你的任务是求出这个最大和的值。

The first line contains two space-separated integers $n$ ($1 \le n \le 2\cdot10^5$) and $q$ ($1 \le q \le 2\cdot10^5$) — the number of elements in the array and the number of queries, correspondingly.

The next line contains $n$ space-separated integers $a_i$ ($1 \le a_i \le 2\cdot10^5$) — the array elements.

Each of the following $q$ lines contains two space-separated integers $l_i$ and $r_i$ ($1 \le l_i \le r_i \le n$) — the $i$-th query.

第一行包含两个以空格分隔的整数 $n$（$1 \le n \le 2\cdot10^5$）和 $q$（$1 \le q \le 2\cdot10^5$）——分别表示数组的元素个数和查询次数。

第二行包含 $n$ 个以空格分隔的整数 $a_i$（$1 \le a_i \le 2\cdot10^5$）——表示数组元素。

接下来的 $q$ 行，每行包含两个以空格分隔的整数 $l_i$ 和 $r_i$（$1 \le l_i \le r_i \le n$）——表示第 $i$ 个查询。

In a single line print, a single integer — the maximum sum of query replies after the array elements are reordered.

Please, do not use the %lld specifier to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specifier.

在一行中输出一个整数——数组元素重排后所有查询回答的最大总和。

请注意，在 C++ 中读取或写入 64 位整数时，请勿使用 %lld 说明符。推荐使用 cin、cout 流，或 %I64d 说明符。