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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC_D
{
    class D058
    {
        static int _Mod = 1000000007;

        static void Main(string[] args)
        {
            int[] h = Console.ReadLine().Split(' ').Select(z => int.Parse(z)).ToArray();
            int n = h[0], m = h[1];
            int[] x = Console.ReadLine().Split(' ').Select(z => int.Parse(z)).ToArray();
            int[] y = Console.ReadLine().Split(' ').Select(z => int.Parse(z)).ToArray();

            long sumY = 0, sum = 0;
            for (int i = 1; i < m; i++)
            {
                long areaY = y[i] - y[i - 1];
                long cnty = (long)i * (m - i); cnty %= _Mod;
                sumY += areaY * cnty; sumY %= _Mod;
            }

            for(int j = 1; j < n; j++)
            {
                long cntx = (long)j * (n - j); cntx %= _Mod;
                long cut = sumY * (x[j] - x[j - 1]); cut %= _Mod;
                cut *=  cntx; cut %= _Mod;
                sum += cut; sum %= _Mod;
            }

            Console.WriteLine(sum);
        }

    }
}