19525번 - Rectangle-free Grid 스페셜 저지다국어

Construct an $N \times N$ grid with the following conditions:

• $2 \leq N \leq 150$
• Each cell is filled with either 'O' or '.'.
• There are at least 1700 cells with 'O'.
• For each tuple of four integers $i, j, k, l$ such that $1 \leq i < j \leq N$ and $1 \leq k < l \leq N$, at least one of the four cells $(i,k)$, $(i,l)$, $(j,k)$, $(j,l)$ is filled with '.'.

There is no input.

The first line should contain an integer $N$. The following $N$ lines should contain $N$ characters each ('O' or '.'), and these $N$ lines describe the grid.

Output for this example satisfies all conditions but the third (number of 'O' in the grid).