w,h=map(int,input().split())
g=[list(input()) for _ in range(h)]
cave1=[];cave2=[]
def dfs(y,x,lis):
    g[y][x]='#'
    lis.append((y,x))
    dy=[0,1,0,-1];dx=[1,0,-1,0]
    for i in range(4):
        ny=y+dy[i];nx=x+dx[i]
        if not (0<=ny<h and 0<=nx<w):
            continue
        if g[ny][nx]=='.':
            dfs(ny,nx,lis)
first=True
for i in range(h):
    for j in range(w):
        if g[i][j]=='.':
            if first:
                dfs(i,j,cave1)
                first=False
            else:
                dfs(i,j,cave2)
ans=1<<60
for y1,x1 in cave1:
    for y2,x2 in cave2:
        ans=min(ans,abs(y2-y1)+abs(x2-x1)-1)
print(ans)