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 9.2.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
using namespace std;
///Welcome to Nasif's Code
#define bug printf("bug\n");
#define bug2(var) cout<<#var<<" "<<var<<endl;
#define co(q) cout<<q<<endl;
#define all(q) (q).begin(),(q).end()
typedef long long int ll;
typedef unsigned long long int ull;
const int MOD = (int)1e9+7;
const int MAX = 1e6;
#define pi acos(-1)
#define inf 1000000000000000LL
#define FastRead    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
ll dist(ll x,ll y)
{
    if(x<=0 && y<=0)
        return abs(abs(x)-abs(y));
    else if(x<=0 && y>=0)
        return abs(x)+y;
    else
        return y-x;
}
ll sum(int n,ll ARR[])
{
    ll res=0;
    for(int i=0; i<n; i++)
    {
        res+=(((ARR[i]*(i+1))%MOD)*(n-i))%MOD;
        res%=MOD;
    }
    return res;
}
int main()
{
    FastRead
    //freopen("output.txt", "w", stdout);
    ll n,m;
    cin>>n>>m;
    ll x[n+5],y[m+5];
    for(int i=0; i<n; i++)
    {
        cin>>x[i];
        if(i)
            x[i-1]=dist(x[i-1],x[i]);
    }
    for(int i=0; i<m; i++)
    {
        cin>>y[i];
        if(i)
            y[i-1]=dist(y[i-1],y[i]);
    }
    cout<<(sum(n-1,x)*sum(m-1,y))%MOD<<endl;





    return 0;
}