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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

fun main(args: Array<String>) {
    val (n,m)= readLine()!!.split(" ").map { it.toInt() }
    val x = readLine()!!.split(" ").map { it.toInt() }
    val y = readLine()!!.split(" ").map { it.toInt() }
    val ansx = x.takeLast(n/2).foldIndexed(0){i,acc,it-> acc.mAdd(it.mMul(2*i+1+n%2))}
            .mSub( x.take(n/2).reversed().foldIndexed(0){i,acc,it-> acc.mAdd(it.mMul(2*i+1+n%2))} )
    val ansy = y.takeLast(m/2).foldIndexed(0){i,acc,it-> acc.mAdd(it.mMul(2*i+1+m%2))}
            .mSub( y.take(m/2).reversed().foldIndexed(0){i,acc,it-> acc.mAdd(it.mMul(2*i+1+m%2))} )
    val ans = ansx.mMul(ansy)
    println(ans)
}

const val mod = 1000000007
fun Int.mMul(a : Int) = (this*a.toLong()%mod).toInt()
fun Int.mAdd(a : Int) = if(this+a<mod) this+a else this+a-mod
fun Int.mSub(a : Int) = if(this-a>=0 ) this-a else this-a+mod