Problem:
Score : 500 points

Problem Statement

On a two-dimensional plane, there are m lines drawn parallel to the x axis, and n lines drawn parallel to the y axis.
Among the lines parallel to the x axis, the i-th from the bottom is represented by y = y_i.
Similarly, among the lines parallel to the y axis, the i-th from the left is represented by x = x_i.

For every rectangle that is formed by these lines, find its area, and print the total area modulo 10^9+7.

That is, for every quadruple (i,j,k,l) satisfying 1\leq i < j\leq n and 1\leq k < l\leq m, find the area of the rectangle formed by the lines x=x_i, x=x_j, y=y_k and y=y_l, and print the sum of these areas modulo 10^9+7.

Constraints

2 \leq n,m \leq 10^5

-10^9 \leq x_1 < ... < x_n \leq 10^9

-10^9 \leq y_1 < ... < y_m \leq 10^9

x_i and y_i are integers.

Input

Input is given from Standard Input in the following format:

n m
x_1 x_2 ... x_n
y_1 y_2 ... y_m

Output

Print the total area of the rectangles, modulo 10^9+7.

Sample Input 1

3 3
1 3 4
1 3 6

Sample Output 1

60

The following figure illustrates this input:

The total area of the nine rectangles A, B, ..., I shown in the following figure, is 60.

Sample Input 2

6 5
-790013317 -192321079 95834122 418379342 586260100 802780784
-253230108 193944314 363756450 712662868 735867677

Sample Output 2

835067060

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

class P
{
    static void Main(string[] _)
    {
        _ = Console.ReadLine().Split(' ');
        int n = int.Parse(_[0]);
        int m = int.Parse(_[1]);
        Int64[] x = new Int64[n];
        Int64[] y = new Int64[m];

        _ = Console.ReadLine().Split(' ');
        for (int i = 0; i < n; i++)
        {
            x[i] = Int64.Parse(_[i]);
        }
        _ = Console.ReadLine().Split(' ');
        for (int i = 0; i < m; i++)
        {
            y[i] = Int64.Parse(_[i]);
        }
        Int64 xx = 0;
        for (int i = 1; i <= n; i++)
        {
            xx += ((i - 1) * x[i - 1] - (n - i) * x[i - 1]);
        }
        Int64 yy = 0;
        for (int i = 1; i <= m; i++)
        {
            yy += ((i - 1) * y[i - 1] - (m - i) * y[i - 1]);
        }

        Console.WriteLine(((xx % 1000000007) * (yy % 1000000007)) % 1000000007);
    }
}