Coin Grid

There is an n \times n grid whose each square is empty or has a coin. On each move, you can remove all coins in a row or column. What is the minimum number of moves after which the grid is empty? Input The first input line has an integer n: the size of the grid. The rows and columns are numbered 1,2,\dots,n. After this, there are n lines describing the grid. Each line has n characters: each ch