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.IO;
using System.Globalization;
using System.Diagnostics;
using static System.Console;
using Pair = System.Collections.Generic.KeyValuePair<int, int>;

class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().Solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    Random rnd = new Random();
    Stopwatch sw = new Stopwatch();
    readonly int[] dd = { 0, 1, 0, -1, 0 };
    readonly int mod = 1000000007;
    readonly string alfa = "abcdefghijklmnopqrstuvwxyz";

    int N, M;
    void Solve()
    {
        N = cin.Nextint;
        M = cin.Nextint;
        var X = cin.Scanlong;
        var Y = cin.Scanlong;
        long X_SUM = 0, Y_SUM = 0;
        long X_CNT = 0, Y_CNT = 0;
        long X_RES = 0, Y_RES = 0;
 
        for (int i = 0; i < N; i++)
        {
            X_SUM = (X_SUM + X[i]) % mod;

        }
        for (int i = 0; i < M; i++)
        {
            Y_SUM = (Y_SUM + Y[i]) % mod;
        }

        for (int i = 0; i < N - 1; i++)
        {
            X_CNT = (X_CNT + X[i]) % mod;
            X_RES = (X_RES + X_SUM - X_CNT) % mod;
            X_RES = (X_RES - (N - 1 - i) * X[i]) % mod;
        }

        for (int i = 0; i < M - 1; i++)
        {
            Y_CNT = (Y_CNT + Y[i]) % mod;
            Y_RES = (Y_RES + Y_SUM - Y_CNT) % mod;
            Y_RES = (Y_RES - (M - 1 - i) * Y[i]) % mod;
        }
        /*while (X_RES < 0)
        {
            X_RES += mod;
        }*/


        /*while (Y_RES < 0)
        {
            Y_RES += mod;
        }*/

        //WriteLine(X_RES);
        //WriteLine(Y_RES);
        WriteLine(X_RES * Y_RES % mod);
    }

}

class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] Scan { get { return ReadLine().Split(); } }
    public int[] Scanint { get { return Array.ConvertAll(Scan, int.Parse); } }
    public long[] Scanlong { get { return Array.ConvertAll(Scan, long.Parse); } }
    public double[] Scandouble { get { return Array.ConvertAll(Scan, double.Parse); } }
    public string Next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return Next;
        }
    }
    public int Nextint { get { return int.Parse(Next); } }
    public long Nextlong { get { return long.Parse(Next); } }
    public double Nextdouble { get { return double.Parse(Next); } }
}