P10045 [AtCoder] AtCoder Beginner Contest 177 - Sum of product of pairs
入门
题目描述

Given are $N integers A_1,\ldots,A_N$.

Find the sum of $A_i \times A_j$ over all pairs (i,j) such that $1\leq i < j \leq N, modulo (10^9+7)$.

Constraints

  • $2 \leq N \leq 2\times 10^5$
  • $0 \leq A_i \leq 10^9$
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
$A_1 \ldots A_N$

Output

Print $\sum_{i=1}^{N-1}\sum_{j=i+1}^{N} A_i A_j, modulo (10^9+7)$.

Examples

Input

3
1 2 3

Output

11

Input

4
141421356 17320508 22360679 244949

Output

437235829

输入格式

见题面

输出格式

见题面

样例输入
3 1 2 3
样例输出
11