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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define N 100000
#define M 100000
#define Q 1000000007

typedef long long int ll;

int add_mod(ll x, ll y, ll q){
	ll ret;

	ret = x + y;
	if(ret >= q) ret -= q;

	return ret;
}

int mul_mod(ll x, ll y, ll q){
	ll ret;

	ret = (x * y) % q;

	return ret;
}

ll x[N], y[M];

int main(void){
	int n, m;
	int i;
	ll ret, tmpx=0, tmpy=0;

	scanf("%d %d", &n, &m);
	for(i=0; i<n; i++) scanf("%lld", &x[i]);
	for(i=0; i<m; i++) scanf("%lld", &y[i]);
	
	for(i=0; i<n; i++)
		tmpx = add_mod(tmpx, mul_mod(add_mod(2*i, 0-n+1, Q) ,x[i], Q), Q);
	for(i=0; i<m; i++)
		tmpy = add_mod(tmpy, mul_mod(add_mod(2*i, 0-m+1, Q) ,y[i], Q), Q);
	ret = mul_mod(tmpx, tmpy, Q);
	
	printf("%lld\n", ret);

	return 0;
}