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<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e8;
const ll INF=1e16;
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
#define MOD 1000000007
// a^b mod MOD
ll powmod(ll a,ll b){
	ll out=1;
	ll p=a%MOD;
	while(b){
		if(b&1)out=out*p%MOD;
		p=p*p%MOD;
		b>>=1;
	}
	return out;
}
int main(){
	int n,m;
	cin>>n>>m;
	vi a(n);
	rep(i,n)cin>>a[i];
	vi b(m);
	rep(i,m)cin>>b[i];
	ll out=0;
	ll sum=0,sum1=0;
	rep(i,n-1){
		ll t=(i+1)*(n-i-1)%MOD;
		ll s=(a[i+1]-a[i])%MOD;
		sum+=t*s;
		sum%=MOD;
//		out+=s*t%MOD;
//		out%=MOD;
	}
	rep(i,m-1){
		ll t=(i+1)*(m-i-1)%MOD;
		ll s=(b[i+1]-b[i])%MOD;
		sum1+=t*s;
		sum1%=MOD;
//		out+=s*t%MOD;
//		out%=MOD;
	}
	cout<<sum*sum1%MOD<<endl;
//	cout<<out<<endl;
}