Rectangle-free Grid

아직 제출이 없습니다시간 제한1초메모리 제한256 MB

문제 설명

예제1

문제

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 '.'.

입력

There is no input.

출력

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.

힌트

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