# [Usaco2005 Jan]Moo Volume 牛的呼声

时间限制：1s 空间限制：64MB

### 题目描述

Farmer John has received a noise complaint from his neighbor, Farmer Bob, stating that his cows are making too much noise. FJ's N cows (1 <= N <= 10,000) all graze at various locations on a long one-dimensional pasture. The cows are very chatty animals. Every pair of cows simultaneously carries on a conversation (so every cow is simultaneously MOOing at all of the N-1 other cows). When cow i MOOs at cow j, the volume of this MOO must be equal to the distance between i and j, in order for j to be able to hear the MOO at all. Please help FJ compute the total volume of sound being generated by all N*(N-1) simultaneous MOOing sessions.

### 输入格式

* Line 1: N * Lines 2..N+1: The location of each cow (in the range 0..1,000,000,000).

### 输出格式

* Line 1: A single integer, the total volume of all the MOOs.

### 样例输入

5 1 5 3 2 4 INPUT DETAILS: There are five cows at locations 1, 5, 3, 2, and 4.

### 样例输出

40 OUTPUT DETAILS: Cow at 1 contributes 1+2+3+4=10, cow at 5 contributes 4+3+2+1=10, cow at 3 contributes 2+1+1+2=6, cow at 2 contributes 1+1+2+3=7, and cow at 4 contributes 3+2+1+1=7. The total volume is (10+10+6+7+7) = 40.

### 提示

没有写明提示

### 题目来源

Silver