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.

45

59

6

13

 #include<cstdio>

 #include<string.h>

 int px[]={-,,,};

 int py[]={,,-,};

 int ans;

 bool key[][];

 char a[][];

 int n,m,x,y;

 void f(int x,int y)

 {

     int nx,ny;

     for(int i =  ;i <  ; i++)

     {

         nx=x+px[i];

         ny=y+py[i];

         if(nx >=  && ny >=  && a[nx][ny] == '.' && key[nx][ny] == false && nx < m && ny < n)

         {

             ans++;

             key[nx][ny]=true;

             f(nx,ny);

         }

     }

 }

 int main()

 {

     while(scanf("%d %d",&n,&m) && n && m)

     {

         memset(key,false,sizeof(key));

         for(int i =  ; i < m ; i++)

         {

             getchar();

             for(int j =  ; j < n ; j++)

             {

                 scanf("%c",&a[i][j]);

                 if(a[i][j] == '@')

                 {

                     x=i;

                     y=j;

                 }

             }

         }

         key[x][y]=true;

         ans=;

         f(x,y);

         printf("%d\n",ans+);

     }

 }