> #include<iostream.h>
> #include<ctype.h>
> #include<stdio.h>
> #include<stdlib.h>
> 
> const int MaxSize=1000;
> 
> typedef struct{
>    int x;
>    int y;
> }PosType;
> 
> typedef struct{
>    int di;
>    PosType pos;
> }SElemType;
> 
> typedef struct{
>     SElemType *base, *top;
> 	int CurSize;
> 	int StackSize;
> }Stack, SType;
> 
> void InitStack(SType*s)
> {
>    s->base=(SElemType*)malloc(sizeof(SElemType)*MaxSize);
>    if(s->base==NULL) cout<<"memery allocation failure"<<endl;
>    s->StackSize=MaxSize;
>    s->CurSize=0;
>    s->top=s->base;
>  
> }
> 
> void Push(SElemType e, SType *s)
> {
>     if(s->CurSize==MaxSize)
> 	{
> 	   cout<<"the stack is full"<<endl;
> 	   return;
> 	}
> 	else{
> 	   *s->top++=e;
> 	   s->CurSize++;
> 	   
> 	}
> }
> 
> void Pop(SElemType&e, SType *s)
> {
>    if(s->base==s->top)
>    {
>      cout<<"the stack is empty"<<endl;
> 	 return;
>    }
>    else e=*--s->top;
> }
> 
> int StackEmpty(SType s)
> {
> 	 if(s.base==s.top) return 1;
> 	 else return 0;
> }
> 
> PosType  NextPos(PosType pt, int d)
> {
> 	switch(d){
> 	  case 1: pt.x+=1; break;
>       case 2: pt.y+=1; break;
> 	  case 3: pt.x-=1; break;
> 	  case 4: pt.y-=1; break;
> 	  default: cout<<"wrong direction"<<endl;
>     }
> 	return pt;
> }
> 
> void print(char m[][25], int r, int c)
> {
> 	 for(int i=0; i<r; i++){
> 		 for(int j=0; j<c; j++)
> 			 cout<<m[i][j]<<' ';
> 	     cout<<endl;
> 	}
> }
> 
> 
>     
> int main()
> {
>    int step, i, j, w, h;
>    char maze[25][25], c;
>    PosType start, CurPos;
>    SType s;
>    SElemType e;
> 
>   
>    
> 
>    while(1)
>    {
>      cin>>w>>h;
> 	 if(w==0&&h==0) break;
> 	 InitStack(&s);
>      
> 	 for(i=1; i<=h; i++)
> 		 for(j=1; j<=w; j++){
> 			 cin>>maze[i][j];
> 			 if(maze[i][j]=='@'){
> 				 start.x=i; start.y=j;
> 			 }
> 		 }
> 	 for(i=0; i<=w+1; i++){ maze[0][i]='#';maze[h+1][i]='#';}
> 	 for(i=0; i<=h+1; i++){maze[i][0]='#';maze[i][w+1]='#';}
> 	 step=0;
>      CurPos=start;
> 	 
> 	 do
> 	 {
> 		 if(maze[CurPos.x][CurPos.y]=='.' || maze[CurPos.x][CurPos.y]=='@')
> 		 {
> 			 
>              e.di=1; e.pos=CurPos; Push(e, &s); 
> 			 step++;
> 			 maze[CurPos.x][CurPos.y]='w';
> 		     CurPos=NextPos(CurPos, 1);
> 		     
> 		 }
> 		 else{
> 			 
> 			 if(!StackEmpty(s)){
> 			    Pop(e, &s);
> 			    if(e.di==4) maze[e.pos.x][e.pos.y]='w';
> 			    while(!StackEmpty(s)&&e.di==4){
> 			       Pop(e,&s);
> 				   maze[e.pos.x][e.pos.y]='w';
> 				}//while
> 			    if(e.di<4){
> 			       e.di++; Push(e, &s);
> 				   CurPos=NextPos(e.pos, e.di);
> 				}//if
> 			 }//if
> 		 }//else
> 	 }while(!StackEmpty(s));
> 	 cout<<step<<endl;
> 	 //print(maze, h+2, w+2);
> 	 free(s.base);
>    }//
>    return 0;
> }