You may have heard of the game Tetris Battle on Facebook,
it's was once popular and you may even have played it before.
You, after Tetris Battle closed down on May 31, 2019,
haven't played a Tetris game for a while.
Since there is no more Tetris Battle to play,
you decide to build one by yourself.
The game field of the tetris has N rows and M columns,
and there are already some piecies that is already placed on the field,
we mark them as character 'x',
and other field that hasn't been occupied by piecies are marked as character '.'.
Now, there is a falling piece, marked as 'o',
and the player want to drop the falling piece directly.
The falling piece will descend until it touch the bottom of the field,
or it land on pieces that were placed before.
If a row is completed, the row will disappear and all rows above will fall one level.
Your mission is to tell after the falling piece landed,
and all completed rows are eliminated,
what will the game field looks like?
ouo.
For sample 1,
the input is:
8 9
..o......
.oo......
..o......
.........
.........
x..xxxxxx
x..xxxxxx
xx.xxxxxx
so the falling piece will descend 5 levels until it touch the bottom of the game field, and becomes:
.........
.........
.........
.........
.........
x.oxxxxxx
xooxxxxxx
xxoxxxxxx
and since the last 2 rows are completed, so they disappear and the third row from last falls 2 levels and becomes:
.........
.........
.........
.........
.........
.........
.........
x.xxxxxxx
For sample 2,
..o...... ......... .........
..o...... ......... .........
..o...... ......... .........
..o...... ......... .........
......... ......... .........
......... => ......... => .........
......... ......... .........
xx.xxxxxx xxoxxxxxx .........
xx.xxx.xx xxoxxx.xx .........
x..xxxxxx x.oxxxxxx xxxxxx.xx
xx.xxxxxx xxoxxxxxx x.xxxxxxx
For sample 3:
....... ....... .......
...oo.. ....... .......
..oo... ....... .......
..o.... ....... .......
....... => ...oo.. => .......
.x..... .xoo... ...xx..
xx.xxxx xxoxxxx .xxx...
x.xxxxx x.xxxxx x.xxxxx
The first line of the input contains 2 integers, N and M,
represent that the game field has N rows and M columns.
After that, there are N lines, each lines contains M character,
the character '.' represent that the cell is empty, not occipied,
the character 'x' represent that the cell is already placed and has been occupied,
the character 'o' represent that the cell is part of the falling piece.
It is a guaranteed that:
1 <= N, M <= 40,
the input game field will always be valid,
and all 'o' character will be connected.
Note that the shape of 'o' will may not be a normal Tetromino, it can be any shape.
Output contains N lines, each line has M character,
output character '.' if the cell is empty and character 'x' if the cell is occipied.