Problem Statement

There is $a H \times W-square$ grid with H horizontal rows and W vertical columns. Let (i, j) denote the square at the i-th row from the top and j-th column from the left.
Each square is described by a character C_{i, j}, where C_{i, j} = . means (i, j) is an empty square, and C_{i, j} = # means (i, j) is a wall.
Takahashi is about to start walking in this grid. When he is on (i, j), he can go to (i, j + 1) or (i + 1, j). However, he cannot exit the grid or enter a wall square. He will stop when there is no more square to go to.
When starting on (1, 1), at most how many squares can Takahashi visit before he stops?

Input

Input is given from Standard Input in the following format:
H W
$C_{1, 1} \ldots C_{1, W}$
$\vdots$
$C_{H, 1} \ldots C_{H, W}$

Output

Print the answer.

Constraints

• $1 \leq H, W \leq 100$
• H and W are integers.
• C_{i, j} = . or C_{i, j} = #. $(1 \leq i \leq H, 1 \leq j \leq W)$
• C_{1, 1} = .

Sample Input 1

3 4
.#..
..#.
..##

Sample Output 1

4

For example, by going $(1, 1) \rightarrow (2, 1) \rightarrow (2, 2) \rightarrow (3, 2),$ he can visit 4 squares.
He cannot visit 5 or more squares, so we should print 4.

Sample Input 2

1 1
.

Sample Output 2

1

Sample Input 3

5 5
.....
.....
.....
.....
.....

Sample Output 3

9

见题面 Input 部分

见题面 Output 部分