Problem 81 » Red and Black

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

45
59
6
13

 

#include<iostream>
using namespace std;
int num,w,h;
char a[21][21];
bool f(int x,int y)
{
   if(x<0||x>=h||y<0||y>=w)
   return 0;
   else
   return 1;
}
void dps(int x,int y)
{
   if(f(x,y)&&a[x][y]=='.')
   {
     a[x][y]='#';
    num++;
    dps(x-1,y);
    dps(x+1,y);
    dps(x,y-1);
    dps(x,y+1);
   }
  
}
int main()
{
    int i,j;
 while(cin>>w>>h&&w!=0&&h!=0)
 {
  for(i=0;i<h;i++)
   for(j=0;j<w;j++)
   cin>>a[i][j];
  num=0;
  for(i=0;i<h;i++)
   for(j=0;j<w;j++)
    if(a[i][j]=='@')
    {
      a[i][j]='.';
     dps(i,j);
    }
  cout<<num<<endl;
 }

}