题目描述
Problem Statement
We have a grid with H rows from top to bottom and W columns from left and right. Initially, the square at the i-th row from the top and j-th column from the left has a lowercase English letter A_{i,j}.
Let us perform Q operations on this grid. In the i-th operation, we are given integers a_i and b_i such that $1\leq a_i \leq H-1$ and $1\leq b_i\leq W-1$, and do the following.
- Let R_1, R_2, R_3, and R_4 be rectangular regions within the grid defined as follows:
- R_1 is the intersection of the top a_i rows and leftmost b_i columns;
- R_2 is the intersection of the top a_i rows and rightmost W-b_i columns;
- R_3 is the intersection of the bottom H-a_i rows and leftmost b_i columns;
-
R_4 is the intersection of the bottom H-a_i rows and rightmost W-b_i columns.
-
Rotate 180 degrees each of R_1, R_2, R_3, and R_4.
Here, a 180-degree rotation of a rectangular region R within the grid moves the character on the square at the i-th from the top and j-th column from the left in R to the square at the i-th from the bottom and j-th column from the right in R. See also the figures for the samples.
Print the grid after all Q operations.
Input
The input is given from Standard Input in the following format:
H W
$A_{1,1}\cdots A_{1, W}$
$\vdots$
$A_{H,1}\cdots A_{H, W}$
Q
a_1 b_1
$\vdots$
a_Q b_Q
Output
Print the grid after the operations in the following format, where B_{i,j} is the character on the square (i,j) on the final grid.
$B_{1,1}\cdots B_{1, W}$
$\vdots$
$B_{H,1}\cdots B_{H, W}$
Constraints
- $2\leq H, W$, and HW $\leq 5\times 10^5$.
- A_{i,j} is a lowercase English letter.
- $1\leq Q\leq 2\times 10^5$
- $1\leq a_i\leq H - 1$
- $1\leq b_i\leq W - 1$
Sample Input 1
4 5
abcde
fghij
klmno
pqrst
1
3 3
Sample Output 1
mlkon
hgfji
cbaed
rqpts
The grid will change as follows.
Sample Input 2
3 7
atcoder
regular
contest
2
1 1
2 5
Sample Output 2
testcon
oderatc
ularreg
The grid will change as follows.
Sample Input 3
2 2
ac
wa
3
1 1
1 1
1 1
Sample Output 3
ac
wa
The grid will change as follows.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分