func main()
	var w: int :: cui@inputInt()
	var h: int :: cui@inputInt()
	var c: [][]char :: #[h][]char
	for i(0, h - 1)
		do c[i] :: cui@input()
	end for
	const ch: char :: 'a'
	var flag: bool :: true
	var ans: int :: w + h
	for y(0, h - 1)
		for x(0, w - 1)
			if(c[y][x] = '.')
				if(flag)
					var dx: []int :: [1, 0, -1, 0]
					var dy: []int :: [0, 1, 0, -1]
					var qu: queue<int> :: #queue<int>
					do qu.add(y * w + x)
					while loop(^qu <> 0)
						var pos: int :: qu.get()
						var cy: int :: pos / w
						var cx: int :: pos % w
						if(c[cy][cx] <> '.')
							skip loop
						end if
						do c[cy][cx] :: ch
						for i(0, 3)
							var nx: int :: cx + dx[i]
							if(nx < 0 | w <= nx)
								skip i
							end if
							var ny: int :: cy + dy[i]
							if(ny < 0 | h <= ny)
								skip i
							end if
							if(c[ny][nx] = '.')
								do qu.add(ny * w + nx)
							end if
						end for
					end while
					do flag :: false
				else
					for dy(-h + 1, h - 1)
						var ny: int :: y + dy
						if(ny < 0 | h <= ny)
							skip dy
						end if
						for dx(-w + 1, w - 1)
							var nx: int :: x + dx
							if(nx < 0 | w <= nx)
								skip dx
							end if
							if(c[ny][nx] = ch)
								do ans :: [ans, dx.abs() + dy.abs() - 1].min()
							end if
						end for
					end for
				end if
			end if
		end for
	end for
	
	do cui@print("\{ans}\n")
end func