Go: package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		w, h := io.NextInt(), io.NextInt()
		if w == 0 {
			break
		}
		xWall := make([][]int, h)
		yWall := make([][]int, h)
		for i := 0; i < h; i++ {
			xWall[i], yWall[i] = make([]int, w), make([]int, w)
			for j := 0; j < w; j++ {
				xWall[i][j], yWall[i][j] = -1, -1
			}
		}
		for i := 0; i < h*2-1; i++ {
			if i%2 == 0 {
				for j := 0; j < w-1; j++ {
					xWall[i/2][j] = io.NextInt()
				}
			} else {
				for j := 0; j < w; j++ {
					yWall[i/2][j] = io.NextInt()
				}
			}
		}
		//io.Println(bfs(w, h, xWall, yWall))
		fmt.Println(bfs(w, h, xWall, yWall))
	}
}

type P struct {
	x, y int
}

func bfs(w, h int, x, y [][]int) int {
	d := make([][]int, h)
	for i := 0; i < h; i++ {
		d[i] = make([]int, w)
	}
	q := list.New()
	q.PushBack(P{0, 0})
	d[0][0] = 1

	for q.Len() != 0 {
		pos := q.Remove(q.Front()).(P)
		if pos.x == w-1 && pos.y == h-1 {
			break
		}
		if pos.x > 0 && x[pos.y][pos.x-1] == 0 && d[pos.y][pos.x-1] == 0 {
			d[pos.y][pos.x-1] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x - 1, pos.y})
		}
		if pos.x < w-1 && x[pos.y][pos.x] == 0 && d[pos.y][pos.x+1] == 0 {
			d[pos.y][pos.x+1] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x + 1, pos.y})
		}
		if pos.y > 0 && y[pos.y-1][pos.x] == 0 && d[pos.y-1][pos.x] == 0 {
			d[pos.y-1][pos.x] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x, pos.y - 1})
		}
		if pos.y < h-1 && y[pos.y][pos.x] == 0 && d[pos.y+1][pos.x] == 0 {
			d[pos.y+1][pos.x] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x, pos.y + 1})
		}
	}
	return d[h-1][w-1]
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

Python: from collections import deque

while True:
  W, H = map(int, input().split())
  if (W,H) == (0,0):
    exit()
  
  # 隣接リストを作る
  adj = [[] for _ in range(W*H)]
  colWall = [None] * H
  rowWall = [None] * (H-1)
  
  for i in range(H):
    colWall[i] = list(map(int, input().split()))
    if i < H-1:
      rowWall[i] = list(map(int, input().split()))
    
  dx = [-1,1,0,0]
  dy = [0,0,-1,1]
  
  for i in range(H):
    for j in range(W):
      for k in range(4):
        y = i + dy[k]
        x = j + dx[k]
        if 0<=x<W and 0<=y<H:
          if k == 0:# 左との比較
            if colWall[i][j-1] == 0:
              adj[W*i+j].append(W*y+x)
          elif k == 1:# 右との比較
            if colWall[i][j] == 0:
              # print(i,j,y,x,colWall)
              adj[W*i+j].append(W*y+x)
          elif k == 2:
            if rowWall[i-1][j] == 0:# 上との比較
              adj[W*i+j].append(W*y+x)
          else:# 下との比較
            if rowWall[i][j] == 0:
              # print(i,j,y,x,rowWall)
              adj[W*i+j].append(W*y+x)
  # print(adj)
  
  queue = deque([0])
  visit = [0] * (W*H)
  visit[0] = 1
  
  while queue:
    now = queue.popleft()
    for u in adj[now]:
      if visit[u] < 1:
        queue.append(u)
        visit[u] = visit[now] + 1
  print(visit[W*H-1])

Python: from collections import deque

while True:
  W, H = map(int, input().split())
  if W == 0 and H == 0:
    break
  
  wall_v = []
  wall_h = []

  wall_h.append([1] * W)
  for _ in range(H-1):
    vertical = list(map(int, input().split()))
    vertical.insert(0, 1)
    vertical.append(1)
    wall_v.append(vertical)
    wall_h.append(list(map(int, input().split())))
  vertical = list(map(int, input().split()))
  vertical.insert(0, 1)
  vertical.append(1)
  wall_v.append(vertical)
  wall_h.append([1] * W)

  q = deque()
  dist = [[0] * W for _ in range(H)]

  dist[0][0] = 1
  q.append([0, 0])

  while len(q) != 0:
    v = q.popleft()
    udlr = ([-1, 0], [1, 0], [0, -1], [0, 1])

    for move in udlr:
      if move == [-1, 0]:
        if wall_h[v[0]][v[1]] == 1:
          continue
      if move == [1, 0]:
        if wall_h[v[0]+1][v[1]] == 1:
          continue
      if move == [0, -1]:
        if wall_v[v[0]][v[1]] == 1:
          continue
      if move == [0, 1]:
        if wall_v[v[0]][v[1]+1] == 1:
          continue
      nv = [0, 0]
      nv[0], nv[1] = v[0] + move[0], v[1] + move[1]
      if dist[nv[0]][nv[1]] != 0:
        continue
      dist[nv[0]][nv[1]] = dist[v[0]][v[1]] + 1
      q.append(nv)

  print(dist[H-1][W-1])

Python: #! cat input | python3 main.py
while True:
    import heapq

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

    walls = []
    for i in range(h * 2 - 1):
        walls.append(list(map(int, input().split())))

    field = [[] for x in range(h * w)]

    for i in range(h):
        for j in range(w):
            f = j + i * w
            if j + 1 < len(walls[i]) and not walls[i*2][j]:
                    field[f].append(f + 1)
                    field[f + 1].append(f)
            if i + 1 < h and not walls[i*2 + 1][j]:
                field[f].append(f + w)
                field[f + w].append(f)
    # print(field)
    end = [False for x in range(w * h)]
    que = [(0, 0, end)]
    goal = h * w - 1
    results = []

    while que:
        tn, cost, end = que[0]
        del que[0]
        for n in field[tn]:
            if n == goal:
                results.append(cost)
            elif not end[n]:
                end[n] = True
                que.append((n, cost + 1, end[:]))

    print(min(results) + 2 if results else 0)