Grid Puzzle I

There is an n \times n grid, and your task is to choose from each row and column some number of squares. How can you do that? Input The first input line has an integer n: the size of the grid. The rows and columns are numbered 1,2,\dots,n. The next line has n integers a_1,a_2,\ldots,a_n: You must choose exactly a_i squares from the ith row. The las line has n integers b_1,b_2,\ldots,b_n: You m