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

def bfs(maze, visited, sy, sx, gy, gx):
    queue = deque([[sy, sx]])
    visited[sy][sx] = 1
    while queue:
      #queueには訪れた地点が入っている。そこから、4方向に移動できるか考え、queueから消す。
        y, x = queue.popleft()#queueに入っていたものを消す。
        if [y, x] == [gy, gx]:#もしゴールについていたならば、そのときの手数を出す。
            return visited[y][x]
        r = ([1, 0, 0], [-1, 0, 1], [0, 1, 2], [0, -1, 3])
        for j, k, l in r:#上下左右についてcheck
          new_y, new_x = y+j, x+k #改行して条件文を続けるときにバックスラッシュ
          if (0 <= new_y < d) and (0 <= new_x < w):
            if visited[new_y][new_x] >= 10 ** 10:#まだ来たことない点だったという条件
              if (l == 0) and (maze[2 * y + 1][x] == 0):
                visited[new_y][new_x] = visited[y][x] + 1
                queue.append([new_y, new_x])#新しい点を足す。
              elif (l == 1) and (maze[2 * y - 1][x] == 0):
                visited[new_y][new_x] = visited[y][x] + 1
                queue.append([new_y, new_x])#新しい点を足す。           
              elif (l == 2) and (maze[2 * y][x] == 0):
                visited[new_y][new_x] = visited[y][x] + 1
                queue.append([new_y, new_x])#新しい点を足す。                   
              elif (l == 3) and (maze[2 * y][x - 1] == 0):
                visited[new_y][new_x] = visited[y][x] + 1
                queue.append([new_y, new_x])#新しい点を足す。 
                
                
T = True
while T:
  w, d = map(int, input().split())
  if (w, d) == (0, 0):
    T = False
    quit()
  visited = [[float("inf")] * w for i in range(d)]
  visited2 = [[0] * w for i in range(d)]
  visited[0][0] = 1
  visited2[0][0] = 1
  maze = [0] * (2 * d - 1)
  for i in range(2 * d - 1):
    maze[i] = list(map(int, input().split()))
  #print(maze)
  bfs(maze, visited, 0, 0, d - 1, w - 1)
  #print(visited)
  if visited[d - 1][w - 1] >= 10 ** 10:
    print(0)
  else:
    print(visited[d - 1][w - 1])

Python: while True:
    w, h = map(int, input().split())
    if w == 0:
        break
    tatekabe = []
    yokokabe = []
    for _ in range(h-1):
        tatekabe.append(list(map(int, input().split())))
        yokokabe.append(list(map(int, input().split())))
    tatekabe.append(list(map(int, input().split())))

    field = [[1e10 for i in range(w)] for j in range(h)]
    
    x, y = 0, 0
    field[y][x] = 1
    stack = [[x, y]]
    while True:
        if stack == []:
            break
        x, y = stack.pop()
        c = field[y][x]
        if x != w-1 and tatekabe[y][x] == 0 and c+1 < field[y][x+1]:
            field[y][x+1] = c + 1
            stack.append([x+1, y])
        if x != 0 and tatekabe[y][x-1] == 0 and c+1 < field[y][x-1]:
            field[y][x-1] = c + 1
            stack.append([x-1, y])
        if y != h-1 and yokokabe[y][x] == 0 and c+1 < field[y+1][x]:
            field[y+1][x] = c + 1
            stack.append([x, y+1])
        if y != 0 and yokokabe[y-1][x] == 0 and c+1 < field[y-1][x]:
            field[y-1][x] = c + 1
            stack.append([x, y-1])
    if field[h-1][w-1] == 1e10:
        print(0)
    else:
        print(field[h-1][w-1])