Now, a ninja is planning to sneak into the castle tower from outside the castle. This ninja can easily run on the ground and swim in the moat, but he is not very good at climbing up from the moat, so he wants to enter the moat as few times as possible.

Create a program that takes a sketch of the castle as input and outputs the minimum number of times you have to crawl up from the moat from outside the castle to the castle tower. The sketch of the castle is given as a two-dimensional grid. The symbols drawn on the sketch show the positions of "&" indicating the position of the castle tower and "#" indicating the position of the moat, and "." (Half-width period) at other points. In addition, it is assumed that there is only one castle tower in the castle, and the ninja moves one square at a time in the north, south, east, and west directions when running or swimming, and does not move diagonally.



Input

A sequence of multiple datasets is given as input. The end of the input is indicated by two lines of zeros. Each dataset is given in the following format:


n m
c1,1 c1,2 ... c1, n
c2,1c2,2 ... c2, n
::
cm, 1cm, 2 ... cm, n


The first line gives the east-west width n and the north-south width m (1 ≤ n, m ≤ 100) of the sketch. The following m lines give the information on the i-th line of the sketch. Each piece of information is a character string of length n consisting of the symbols "&", "#", and ".".

The number of datasets does not exceed 50.

Output

Outputs the minimum number of times (integer) that must be climbed from the moat for each dataset on one line.

Examples

Input

5 5
.###.
#...#
#.&.#
#...#
.###.
18 15
..####....####....
####..####....####
#...............##
.#.############.##
#..#..........#.##
.#.#.########.#.##
#..#.#......#.#.##
.#.#....&...#.#.##
#..#........#.#.##
.#.#.########.#.##
#..#..........#.##
.#.############.##
#...............##
.#################
##################
9 10
#########
........#
#######.#
#.....#.#
#.###.#.#
#.#&#.#.#
#.#...#.#
#.#####.#
#.......#
#########
9 3
###...###
#.#.&.#.#
###...###
0 0


Output

1
2
0
0


Input

5 5
.###.
...#
.&.#
...#
.###.
18 15
..####....####....
..####....####
...............##
.#.############.##
..#..........#.##
.#.#.########.#.##
..#.#......#.#.##
.#.#....&...#.#.##
..#........#.#.##
.#.#.########.#.##
..#..........#.##
.#.############.##
...............##
.#################

9 10

........#
.#
.....#.#
.###.#.#
.#&#.#.#
.#...#.#
.#####.#
.......#

9 3
...###
.#.&.#.#
...###
0 0
</pre>


Output

1
2
0
0

Difficulty: UNKNOWN_DIFFICULTY

Starter code:

Solutions:
import sys
from sys import stdin
from collections import deque
input = stdin.readline

def bfs(field, sx, sy):
	dy = [-1, 1, 0, 0]
	dx = [0, 0, -1, 1]
	Y = len(field)
	X = len(field[0])
	d = [[float('inf')] * X for _ in range(Y)]
	moats = set()
	Q = deque()
	Q.append((sx, sy))
	d[sy][sx] = 0
	while Q:
		(cx, cy) = Q.popleft()
		for i in range(4):
			nx = cx + dx[i]
			ny = cy + dy[i]
			if not 0 <= nx < X or not 0 <= ny < Y:
				return (True, moats)
			elif d[ny][nx] == float('inf'):
				if field[ny][nx] == '#':
					moats.add((nx, ny))
				else:
					Q.append((nx, ny))
					d[ny][nx] = d[cy][cx] + 1
	return (False, moats)

def fill_moat(field, moats):
	dy = [-1, 1, 0, 0]
	dx = [0, 0, -1, 1]
	Y = len(field)
	X = len(field[0])
	while moats:
		(cx, cy) = moats.pop()
		field[cy][cx] = '^'
		for i in range(4):
			nx = cx + dx[i]
			ny = cy + dy[i]
			if 0 <= nx < X and 0 <= ny < Y:
				if field[ny][nx] == '#':
					moats.add((nx, ny))

def solve(field):
	start = (0, 0)
	for (y, row) in enumerate(field):
		if '&' in row:
			start = (row.index('&'), y)
	(sx, sy) = start
	climb = 0
	while True:
		(res, moats) = bfs(field, sx, sy)
		if res is False:
			climb += 1
			fill_moat(field, moats)
		else:
			break
	return climb

def main(args):
	while True:
		(n, m) = map(int, input().split())
		if n == 0 and m == 0:
			break
		data = [input().strip('\n') for _ in range(m)]
		field = [list(x) for x in data]
		result = solve(field)
		print(result)
main(sys.argv[1:])


from heapq import heappush, heappop
while True:
	(n, m) = map(int, input().split())
	if n == 0:
		break
	mp = ['X' + input() + 'X' for _ in range(m)]
	mp.insert(0, 'X' * (n + 2))
	mp.append('X' * (n + 2))
	que = []
	visited = [[False] * (n + 2) for _ in range(m + 2)]
	sur_flag = False
	for i in range(1, n + 1):
		if mp[1][i] == '&' or mp[m][i] == '&':
			sur_flag = True
			break
		(c1, s1) = (1, 0) if mp[1][i] == '#' else (0, 1)
		(c2, s2) = (1, 0) if mp[m][i] == '#' else (0, 1)
		heappush(que, (c1, s1, (i, 1)))
		heappush(que, (c2, s2, (i, m)))
		visited[1][i] = True
		visited[m][i] = True
	for i in range(1, m + 1):
		if mp[i][1] == '&' or mp[i][n] == '&':
			sur_flag = True
			break
		(c1, s1) = (1, 0) if mp[i][1] == '#' else (0, 1)
		(c2, s2) = (1, 0) if mp[i][n] == '#' else (0, 1)
		heappush(que, (c1, s1, (1, i)))
		heappush(que, (c2, s2, (n, i)))
		visited[i][1] = True
		visited[i][n] = True
	if sur_flag:
		print(0)
		continue
	direct = ((0, 1), (0, -1), (1, 0), (-1, 0))
	reached = False
	while que and (not reached):
		(cost, status, point) = heappop(que)
		(x, y) = point
		for (dx, dy) in direct:
			(newx, newy) = (x + dx, y + dy)
			if not visited[newy][newx]:
				visited[newy][newx] = True
				sym = mp[newy][newx]
				if sym == '&':
					print(cost)
					reached = True
					break
				elif sym == '#':
					if status == 1:
						heappush(que, (cost + 1, 0, (newx, newy)))
					else:
						heappush(que, (cost, 0, (newx, newy)))
				elif sym == '.':
					heappush(que, (cost, 1, (newx, newy)))


import sys
from sys import stdin
from collections import deque
input = stdin.readline

def bfs(field, sx, sy):
	dy = [-1, 1, 0, 0]
	dx = [0, 0, -1, 1]
	Y = len(field)
	X = len(field[0])
	d = [[float('inf')] * X for _ in range(Y)]
	moats = set()
	Q = deque()
	Q.append((sx, sy))
	d[sy][sx] = 0
	while Q:
		(cx, cy) = Q.popleft()
		for i in range(4):
			nx = cx + dx[i]
			ny = cy + dy[i]
			if not 0 <= nx < X or not 0 <= ny < Y:
				return (True, moats)
			elif d[ny][nx] == float('inf'):
				if field[ny][nx] == '#':
					moats.add((nx, ny))
				else:
					Q.append((nx, ny))
					d[ny][nx] = d[cy][cx] + 1
	return (False, moats)

def fill_moat(field, moats):
	dy = [-1, 1, 0, 0]
	dx = [0, 0, -1, 1]
	Y = len(field)
	X = len(field[0])
	d = [[float('inf')] * X for _ in range(Y)]
	while moats:
		(cx, cy) = moats.pop()
		field[cy][cx] = '^'
		for i in range(4):
			nx = cx + dx[i]
			ny = cy + dy[i]
			if 0 <= nx < X and 0 <= ny < Y and (d[ny][nx] == float('inf')):
				if field[ny][nx] == '#':
					moats.add((nx, ny))
					d[ny][nx] = d[cy][cx] + 1

def solve(field):
	start = (0, 0)
	for (y, row) in enumerate(field):
		if '&' in row:
			start = (row.index('&'), y)
	(sx, sy) = start
	climb = 0
	while True:
		(res, moats) = bfs(field, sx, sy)
		if res is False:
			climb += 1
			fill_moat(field, moats)
		else:
			break
	return climb

def main(args):
	while True:
		(n, m) = map(int, input().split())
		if n == 0 and m == 0:
			break
		data = [input().strip('\n') for _ in range(m)]
		field = [list(x) for x in data]
		result = solve(field)
		print(result)
main(sys.argv[1:])


from heapq import heappush, heappop
while True:
	(n, m) = map(int, input().split())
	if n == 0:
		break
	mp = ['X' + input() + 'X' for _ in range(m)]
	mp.insert(0, 'X' * (n + 2))
	mp.append('X' * (n + 2))
	que = []
	visited = [[False] * (n + 2) for _ in range(m + 2)]
	sur_flag = False
	for i in range(1, n + 1):
		if mp[1][i] == '&' or mp[m][i] == '&':
			sur_flag = True
			break
		(c1, s1) = (1, 0) if mp[1][i] == '#' else (0, 1)
		(c2, s2) = (1, 0) if mp[m][i] == '#' else (0, 1)
		heappush(que, (c1, s1, (i, 1)))
		heappush(que, (c2, s2, (i, m)))
		visited[1][i] = True
		visited[m][i] = True
	for i in range(1, m + 1):
		if mp[i][1] == '&' or mp[i][n] == '&':
			sur_flag = True
			break
		(c1, s1) = (1, 0) if mp[i][1] == '#' else (0, 1)
		(c2, s2) = (1, 0) if mp[i][n] == '#' else (0, 1)
		heappush(que, (c1, s1, (1, i)))
		heappush(que, (c2, s2, (n, i)))
		visited[i][1] = True
		visited[i][n] = True
	if sur_flag:
		print(0)
		continue
	direct = ((0, 1), (0, -1), (1, 0), (-1, 0))
	reached = False
	while que and (not reached):
		(cost, status, point) = heappop(que)
		(x, y) = point
		for (dx, dy) in direct:
			(newx, newy) = (x + dx, y + dy)
			if not visited[newy][newx]:
				visited[newy][newx] = True
				if mp[newy][newx] == '&':
					print(cost)
					reached = True
					break
				elif mp[newy][newx] == '#':
					if status == 1:
						heappush(que, (cost + 1, 0, (newx, newy)))
					else:
						heappush(que, (cost, 0, (newx, newy)))
				elif mp[newy][newx] == '.':
					heappush(que, (cost, 1, (newx, newy)))


from collections import deque
dd = ((-1, 0), (0, -1), (1, 0), (0, 1))
while 1:
	(N, M) = map(int, input().split())
	if N == M == 0:
		break
	MP = [input() for i in range(M)]
	cost = [[-1] * N for i in range(M)]
	cur = 0
	que = deque()
	for i in range(M):
		for j in range(N):
			if MP[i][j] == '&':
				que.append((i, j))
				cost[i][j] = 0
	while que:
		(r, c) = que.popleft()
		s = cost[r][c]
		a = MP[r][c]
		for (dr, dc) in dd:
			nr = r + dr
			nc = c + dc
			if not 0 <= nr < M or not 0 <= nc < N or cost[nr][nc] != -1:
				continue
			b = MP[nr][nc]
			t = s + (a != '#' and b == '#')
			cost[nr][nc] = t
			if s == t:
				que.appendleft((nr, nc))
			else:
				que.append((nr, nc))
	ans = N * M
	for i in range(M):
		ans = min(ans, cost[i][0], cost[i][-1])
	for i in range(N):
		ans = min(ans, cost[0][i], cost[-1][i])
	print(ans)