简单dfs
#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cmath>
using namespace std;
int f[4][2]={0,1,1,0,0,-1,-1,0};
char a[21][21];
int tmp,n,m;
void dfs(int x,int y)
{
int x1, y1;
for(int i=0;i<4;i++)
{
x1=x+f[i][0];y1=y+f[i][1];
if(x1<m&&x1>=0&&y1<n&&y1>=0&&a[x1][y1]=='.')
{
a[x1][y1]='#';
tmp++;
dfs(x1,y1);
//a[x1][y1]='.';
}
}
}
int main()
{
int x,y;
while(cin>>n>>m)
{
getchar();
if(n==0&&m==0)
break;
for(int i=0;i<m;i++)
for(int j=0;j<n;j++)
{
cin>>a[i][j];
if(a[i][j] == '@')
{x=i;y=j;}
}
tmp=1;
dfs(x,y);
cout<<tmp<<endl;
}
}