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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <cstdio>
#include <iostream>
#include <cmath>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <cstdlib>
#include <map>
#include <queue>
#include <utility>
#include <vector>
#include <set>
#include <memory.h>
#include <iomanip>
#include <bitset>
#include <list>
#include <stack>
#include <deque>

using namespace std;

#define mod 1000000007

int main()
{
	int n, m;
	cin >> n >> m;
	long long int x[100001], y[100001];
	for(int i = 0; i < n; i++){
		cin >> x[i];
	}
	for(int i = 0; i < m; i++){
		cin >> y[i];
	}
	long long int ansx = 0, ansy = 0;
	for(int i = 1; i < n; i++){
		ansx += (((x[i] - x[i - 1]) % mod) * (i * (n - i)) % mod) % mod;
		ansx = ansx % mod;
	}
	for(int i = 1; i < m; i++){
		ansy += (((y[i] - y[i - 1]) % mod) * (i * (m - i)) % mod) % mod;
		ansy = ansy % mod;
	}
	// cout << ansx << " " << ansy << endl;
	long long int ans = (ansx * ansy) % mod;
	cout << ans << endl;
	return 0;
}