- Time limit: 1.00 s
- Memory limit: 512 MB
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 $-1$.
- $1 \le n \le 1000$