Problem Statement

We have a grid of H horizontal rows and W vertical columns, where some of the squares contain obstacles.
Let (i, j) denote the square at the i-th row from the top and j-th column from the left.
You are given $H strings S_1, S_2, S_3, \dots, S_H$. The j-th character of S_i describes the square (i, j); # means the square contains an obstacle, and . means it does not.
We say a square is visible from another when it is on the same row or the same column, and there is no obstacle between them (including themselves).
Print the number of squares visible from the square (X, Y) (including (X, Y) itself).

Input

Input is given from Standard Input in the following format:
H W X Y
S_1
S_2
S_3
$\hspace{3pt} \vdots$
S_H

Output

Print the answer.

Constraints

• $1 \le H \le 100$
• $1 \le W \le 100$
• $1 \le X \le H$
• $1 \le Y \le W$
• S_i is a string of length W consisting of . and #.
• The square (X, Y) does not contain an obstacle.

Sample Input 1

4 4 2 2

..

...#

.#.

.#.#

Sample Output 1

4

The squares visible from the square (2, 2) are:

• (2, 1)
• (2, 2)
• (2, 3)
• (3, 2)

Sample Input 2

3 5 1 4

....

....#

Sample Output 2

4

Even if two squares are on the same row or the same column, they are not visible from each other when there are obstacles between them.

Sample Input 3

5 5 4 2
.#..#

.

...

..#.

.

Sample Output 3

3

见题面 Input 部分

见题面 Output 部分