Problem Description

There is a rectangular room, covered with square tiles. Each tile is colored either red or black. A man is standing on a black tile. From a tile, he can move to one of four adjacent tiles. But he can't move on red tiles, he can move only on black tiles.

Write a program to count the number of black tiles which he can reach by repeating the moves described above. 

 

Input

The input consists of multiple data sets. A data set starts with a line containing two positive integers W and H; W and H are the numbers of tiles in the x- and y- directions, respectively. W and H are not more than 20.

There are H more lines in the data set, each of which includes W characters. Each character represents the color of a tile as follows.

'.' - a black tile 

'#' - a red tile 

'@' - a man on a black tile(appears exactly once in a data set) 

 

Output

For each data set, your program should output a line which contains the number of tiles he can reach from the initial tile (including itself). 

 

Sample Input

6 9....#......#..............................#@...#.#..#.11 9.#..........#.#######..#.#.....#..#.#.###.#..#.#..@#.#..#.#####.#..#.......#..#########............11 6..#..#..#....#..#..#....#..#..###..#..#..#@...#..#..#....#..#..#..7 7..#.#....#.#..###.###...@...###.###..#.#....#.#..0 0

 

Sample Output

4559613

分析：

只能够走‘.’，递归到最后，看一共有多少个可以走。

代码：

#include 
    
     #include
     
      using namespace std;int m,n;int Next[4][2]= {
   {0,1},{1,0},{0,-1},{-1,0}};int bj[21][21];char a[21][21];int sum=0;void dfs(int x,int y){    int nx,ny;    for(int i=0; i<4; i++)    {        nx=x+Next[i][0];        ny=y+Next[i][1];        if(a[nx][ny]=='.'&&nx>=0&&nx
      
       =0&&ny
       
        >n>>m)    {        if(m==0||n==0)            break;        for(i=0; i
        
         >a[i][j];                if(a[i][j]=='@')                {                    x=i;                    y=j;                }            }        memset(bj,0,sizeof(bj));        sum=1;        dfs(x,y);        cout<
         
          <