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: while True:
    w, h = map(int, input().split())
    vart = []
    hori = []
    if w == 0 and h ==0:
        break
    for i in range(2*h-1):
        if i % 2 == 0:
            vart.append(list(map(int, input().split())))
        else:
            hori.append(list(map(int, input().split())))
    node = [[0 for i in range(h)] for i in range(w)]
    queue = [(0,0,1)]
    res = 0
    while queue:
        p = queue.pop(0)
        x, y, z = p[0], p[1], p[2]
        if x == w-1 and y == h-1:
            res = z
            break
        node[x][y] += 1
        if y-1 >= 0 and hori[y-1][x] == 0 and node[x][y-1] == 0:
            node[x][y-1] = node[x][y]
            queue.append((x,y-1,z+1))
        if y+1 < h and hori[y][x] == 0 and node[x][y+1] == 0:
            node[x][y+1] = node[x][y]
            queue.append((x,y+1,z+1))
        if x-1 >= 0 and vart[y][x-1] == 0 and node[x-1][y] == 0:
            node[x-1][y] = node[x][y]
            queue.append((x-1,y,z+1))
        if x+1 < w and vart[y][x] == 0 and node[x+1][y] == 0:
            node[x+1][y] = node[x][y]
            queue.append((x+1,y,z+1))
    print(res)

Python: from collections import deque

while True:
    w, h = map(int, input().split())
    if w == 0:
        break
    lr_walls = []
    ud_walls = []
    for i in range(2 * h - 1):
        wall = list(map(int, input().split()))
        if i % 2 == 0:
            lr_walls.append(wall)
        else:
            ud_walls.append(wall)
    checked = [[False] * w for _ in range(h)]
    checked[0][0] = True
    que = deque()
    que.append((1, 0, 0))
    while que:
        score, x, y = que.popleft()
        if (x, y) == (w - 1, h - 1):
            print(score)
            break

        if x < w - 1 and lr_walls[y][x] == 0 and not checked[y][x + 1]:
            checked[y][x + 1] = True
            que.append((score + 1, x + 1, y))

        if x > 0 and lr_walls[y][x - 1] == 0 and not checked[y][x - 1]:
            checked[y][x - 1] = True
            que.append((score + 1, x - 1, y))

        if y < h - 1 and ud_walls[y][x] == 0 and not checked[y + 1][x]:
            checked[y + 1][x] = True
            que.append((score + 1, x, y + 1))

        if y > 0 and ud_walls[y - 1][x] == 0 and not checked[y - 1][x]:
            checked[y - 1][x] = True
            que.append((score + 1, x, y - 1))
    else:
        print(0)

Python: #!/usr/bin/env python3
from queue import Queue

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]

while True:
    w, h = map(int, input().split())
    if w == 0:
        exit()
    wall = [list(map(int, input().split())) for _ in range(2 * h - 1)]

    d = [[0] * w for _ in range(h)]
    d[0][0] = 1

    q = Queue()
    q.put((0, 0))
    while not q.empty():
        sy, sx = q.get()
        for i in range(4):
            ty = sy + dy[i]
            tx = sx + dx[i]
            if tx < 0 or w - 1 < tx or ty < 0 or h - 1 < ty:
                continue
            if d[ty][tx] > 0:
                continue
            if wall[sy + ty][(sx + tx) // 2] == 1:
                continue

            d[ty][tx] = d[sy][sx] + 1
            q.put((ty, tx))

    print(d[-1][-1])

Python: from collections import deque

while True:
    W, H = map(int, input().split(' '))
    if W == 0 and H == 0:
        break

    field = []
    for _ in range(2 * H - 1):
        row = list(input())
        if len(row) == 2 * W - 2:
            row.append(' ')
        field.append(row)

    gy = 2 * H - 2
    gx = 2 * W - 2

    queue = deque()
    queue.append((0, 0, 1))

    min_step = 0
    while len(queue) > 0:
        y, x, step = queue.popleft()
        if field[y][x] != ' ':
            continue
        else:
            field[y][x] = 'X'

        if y == gy and x == gx:
            min_step = step
            break

        for dy, dx in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
            if 0 <= y + dy <= gy and 0 <= x + dx <= gx:
                if field[y + dy][x + dx] == '0':
                    queue.append((y + 2 * dy, x + 2 * dx, step + 1))

    print(min_step)