CF903D Almost Difference

Description

Let's denote a function ![](https://cdn.luogu.com.cn/upload/vjudge_pic/CF903D/775e2389c0046855a8c7f1a2f9b05b0f64f8c0ab.png) You are given an array $ a $ consisting of $ n $ integers. You have to calculate the sum of $ d(a_{i},a_{j}) $ over all pairs $ (i,j) $ such that $ 1

Input Format

N/A

Output Format

N/A

Explanation/Hint

In the first example: 1. $ d(a_{1},a_{2})=0 $ ; 2. $ d(a_{1},a_{3})=2 $ ; 3. $ d(a_{1},a_{4})=0 $ ; 4. $ d(a_{1},a_{5})=2 $ ; 5. $ d(a_{2},a_{3})=0 $ ; 6. $ d(a_{2},a_{4})=0 $ ; 7. $ d(a_{2},a_{5})=0 $ ; 8. $ d(a_{3},a_{4})=-2 $ ; 9. $ d(a_{3},a_{5})=0 $ ; 10. $ d(a_{4},a_{5})=2 $ .