Problem Statement

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 $1\leq i < j \leq N, modulo (10^9+7)$.

Input

Input is given from Standard Input in the following format:
N
$A_1 \ldots A_N$

Output

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

Constraints

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

Sample Input 1

3
1 2 3

Sample Output 1

11

We have $1 \times 2 + 1 \times 3 + 2 \times 3 = 11$.

Sample Input 2

4
141421356 17320508 22360679 244949

Sample Output 2

437235829

见题面 Input 部分

见题面 Output 部分