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#F0804. Mice and Holes

    ID: 810 传统题 2000ms 256MiB 尝试: 0 已通过: 0 难度: 9 上传者: 标签>数据结构动态规划贪心排序算法思想编程与模拟挑战难度共享题库Codeforces英文题面题目来源题面语言

Mice and Holes

题目描述

F. Mice and Holes
time limit per test
1.5 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

One day Masha came home and noticed n mice in the corridor of her flat. Of course, she shouted loudly, so scared mice started to run to the holes in the corridor.

The corridor can be represeted as a numeric axis with n mice and m holes on it. ith mouse is at the coordinate xi, and jth hole − at coordinate pj. jth hole has enough room for cj mice, so not more than cj mice can enter this hole.

What is the minimum sum of distances that mice have to go through so that they all can hide in the holes? If ith mouse goes to the hole j, then its distance is |xi-pj|.

Print the minimum sum of distances.

Input

The first line contains two integer numbers n, m (1≤n,m≤5000) − the number of mice and the number of holes, respectively.

The second line contains n integers x1,x2,...,xn (-109xi≤109), where xi is the coordinate of ith mouse.

Next m lines contain pairs of integer numbers pj,cj (-109pj≤109,1≤cj≤5000), where pj is the coordinate of jth hole, and cj is the maximum number of mice that can hide in the hole j.

Output

Print one integer number − the minimum sum of distances. If there is no solution, print -1 instead.

Examples
Input
4 5
6 2 8 9
3 6
2 1
3 6
4 7
4 7
Output
11
Input
7 2
10 20 30 40 50 45 35
-1000000000 10
1000000000 1
Output
7000000130


题目来源:fps-www.educg.net-codeforce-1-2833.xml.zip;FPS 共享题包,题包内第 232 题。保留原作者与原赛事署名。