Score : 500 points
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.
Input is given from Standard Input in the following format:
n m x_1 x_2 ... x_n y_1 y_2 ... y_m
Print the total area of the rectangles, modulo 10^9+7.
3 3 1 3 4 1 3 6
60
The following figure illustrates this input:
The total area of the nine rectangles A, B, ..., I shown in the following figure, is 60.
6 5 -790013317 -192321079 95834122 418379342 586260100 802780784 -253230108 193944314 363756450 712662868 735867677
835067060