Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1



Fixed submission:
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1



Fixed submission:
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1



Fixed submission:
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1



Fixed submission:
# -*- coding: utf-8 -*-
#rea and blac
h,w=1,1

count=0

def search(x,y):
    #マップの外側か壁の場合は何もしない
    #print(x,y)
    global count
    if x<0 or x>w-1 or y<0 or y>h-1 or map_data[y][x]=='#':
 
        return
        
    
    #以前に到達していたら何もしない
    if reached[y][x]:
         return

    reached[y][x]=1
    count+=1
    #print("aa")



    search(x+1,y)#右
    search(x-1,y)#左
    search(x,y+1)#上
    search(x,y-1)#下
    



while h!=0 and w!=0: 

    count=0
    #グラフの入力方法------

    w,h=map(int ,raw_input().split())
    if h==0 and w==0:
        break

    map_data = [[0]*w for _ in range(h)]
    reached = [[0]*w for _ in range(h)]
    for i in range(h):
        ct = raw_input()
        #print(len(ct))
        for j in range(w):
            map_data[i][j] = ct[j]
            if ct[j]=="@":
                sx=j
                sy=i

    #------



    search(sx,sy)

    print(count)
    count=0
    w=1
    h=1