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 == 0 and h == 0:
        break
    v_wall = [[0] * w for _ in range(h)]
    h_wall = [[0] * w for _ in range(h)]
    for i in range(2 * h - 1):
        walls = map(int, input().split())
        for j, obstacle in enumerate(walls):
            if i % 2 == 0:
                v_wall[i // 2][j] = obstacle
            else:
                h_wall[i // 2][j] = obstacle
    d = [[False] * w for _ in range(h)]
    que = deque()
    sx, sy = 0, 0
    gx, gy = w-1, h-1
    que.append((sx, sy))
    d[sy][sx] = 0

    while que:
        x, y = que.popleft()
        for dx, dy in [[-1, 0], [1, 0], [0, 1], [0, -1]]:
            nx, ny = x + dx, y + dy
            # 0 index
            if 0 <= nx < w and 0 <= ny < h and d[ny][nx] is False:
                if dy == 1:
                    if h_wall[y][x] == 0:
                        d[ny][nx] = d[y][x] + 1
                        que.append((nx, ny))
                elif dy == -1:
                    if h_wall[ny][nx] == 0:
                        d[ny][nx] = d[y][x] + 1
                        que.append((nx, ny))
                elif dx == 1:
                    if v_wall[y][x] == 0:
                        d[ny][nx] = d[y][x] + 1
                        que.append((nx, ny))
                elif dx == -1:
                    if v_wall[ny][nx] == 0:
                        d[ny][nx] = d[y][x] + 1
                        que.append((nx, ny))
    if d[gy][gx] is False:
        print(0)
    else:
        print(d[gy][gx] + 1)

Python: import collections
while True:
    W, H = map(int, input().split())
    if (W, H) == (0, 0): break
    cdoor, rdoor = [], []
    cdoor.append(list(map(int, input().split())))
    for _ in range(H-1):
        rdoor.append(list(map(int, input().split())))
        cdoor.append(list(map(int, input().split())))
    
    maze = [[-1 for _ in range(W)] for _ in range(H)]
    maze[0][0] = 1
    que = collections.deque()
    que.append((0, 0))
    drc = [(-1, 0), (0, 1), (1, 0), (0, -1)]
    while maze[H-1][W-1] == -1 and len(que) > 0:
        r, c = que.popleft()
        for dr, dc in drc:
            nr, nc = r+dr, c+dc
            if 0 <= nr < H and 0 <= nc < W and ((dc == 0 and rdoor[min(nr, nr-dr)][c] == 0) or (dr == 0 and cdoor[r][min(nc, nc-dc)] == 0)) and maze[nr][nc] == -1:
                maze[nr][nc] = maze[r][c] + 1
                que.append((nr, nc))
    print(maze[H-1][W-1] if maze[H-1][W-1] != -1 else 0)