P6063 [CF938E] Max History
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题目描述

You are given an array a of length n. We define fa the following way:

  • Initially fa = 0, M = 1;
  • for every 2 ≤ i ≤ n if aM < ai then we set fa = fa + aM and then set M = i.

Calculate the sum of fa over all n! permutations of the array a modulo 109 + 7.

Note: two elements are considered different if their indices differ, so for every array a there are exactly n! permutations.

Input

The first line contains integer n (1 ≤ n ≤ 1 000 000) — the size of array a.

Second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 109).

Output

Print the only integer, the sum of fa over all n! permutations of the array a modulo 109 + 7.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
2 1 3
样例输出
1
提示

For the second example all the permutations are:

  • p = [1, 2, 3] : fa is equal to 1;
  • p = [1, 3, 2] : fa is equal to 1;
  • p = [2, 1, 3] : fa is equal to 1;
  • p = [2, 3, 1] : fa is equal to 1;
  • p = [3, 1, 2] : fa is equal to 0;
  • p = [3, 2, 1] : fa is equal to 0.

Where p is the array of the indices of initial array a. The sum of fa is equal to 4.