【OJ】Red and black poj1979 // acmclub.com 6659

#include<iostream>
#include<cstdio>
using namespace std;
char tiles[21][21];
int x,y,w,h,ans;
int dx[4]={-1,0,0,1},dy[4]={0,-1,1,0};//^<>
void dfs(int sx,int sy){
	ans++;tiles[sy][sx]='#';
	for(int i=0;i<4;i++){
		int nx=sx+dx[i],ny=sy+dy[i];
		if(nx>=1&&nx<=w&&ny>=1&&ny<=h&&tiles[ny][nx]=='.'/**/)dfs(nx,ny); 
	}
}
int main(){
//	freopen("red.txt","r",stdin);
	while(cin>>w>>h&&(w||h)){
		 ans=0;		getchar();
		for(int i=1;i<=h;i++){
	 		for(int j=1;j<=w;j++){
 				tiles[i][j]=getchar();
 				if(tiles[i][j]=='@'){x=j;y=i;}
 			}
	   		getchar();
		}
		dfs(x,y);
		cout<<ans<<endl;			
	}
	
	return 0;
}