- Time limit: 1.00 s
- Memory limit: 512 MB
There is an n \times n grid whose each square is initially white. On each move you can paint one row or column black.
Your task is to create a given target grid using the minimum number of moves.
The first input line has an integer n: the size of the grid.
After this, there are n lines of n characters that describe the target grid. Each color is 0 (white) or 1 (black).
Print the minimum number of moves needed. If the task is impossible, print -1.
- 1 \le n \le 1000
3 001 111 001
3 101 111 001