Problem Statement

There is a grid with H horizontal rows and W vertical columns. Let (i,j) denote the square at the i-th row from the top and the j-th column from the left.
Find the number of squares that share a side with Square (R, C).
Here, two squares (a,b) and (c,d) are said to share a side if and only if |a-c|+|b-d|=1 (where |x| denotes the absolute value of x).

Input

Input is given from Standard Input in the following format:
H W
R C

Output

Print the answer as an integer.

Constraints

• All values in input are integers.
• $1 \le R \le H \le 10$
• $1 \le C \le W \le 10$

Sample Input 1

3 4
2 2

Sample Output 1

4

We will describe Sample Inputs/Outputs 1,2, and 3 at once below Sample Output 3.

Sample Input 2

3 4
1 3

Sample Output 2

3

Sample Input 3

3 4
3 4

Sample Output 3

2

When H=3 and W=4, the grid looks as follows.

• For Sample Input 1, there are 4 squares adjacent to Square (2,2).
• For Sample Input 2, there are 3 squares adjacent to Square (1,3).
• For Sample Input 3, there are 2 squares adjacent to Square (3,4).

Sample Input 4

1 10
1 5

Sample Output 4

2

Sample Input 5

8 1
8 1

Sample Output 5

1

Sample Input 6

1 1
1 1

Sample Output 6

0

见题面 Input 部分

见题面 Output 部分