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(start):
    Q = deque()
    Q.append(start)
    child = deque()
    dist[start[1]][start[0]] = 0

    while Q:
        x, y = Q.popleft()

        for i in range(4):
            child.clear()
            nx = x + dx[i]
            ny = y + dy[i]

            if nx < 0 or nx >= W or ny < 0 or ny >= H:
                continue
            if G[y][x][i] == 1:
                continue
            if dist[ny][nx] != -1:
                continue

            child.append((nx, ny))

            if len(child) > 0:
                for c in child:
                    dist[c[1]][c[0]] = dist[y][x] + 1
                    Q.append(c)


W, H = map(int, input().split())
while not (W == 0 and H == 0):
    G = [[[0 for _ in range(4)] for _ in range(W)] for _ in range(H)]

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

    for i in range(H):
        for j in range(W):
            if j < W - 1:
                # 右
                G[i][j][0] = w[i][j]
            else:
                G[i][j][0] = 1
            if i < H - 1:
                # 下
                G[i][j][1] = h[i][j]
            else:
                G[i][j][1] = 1
            if j - 1 >= 0:
                # 左
                G[i][j][2] = w[i][j - 1]
            else:
                G[i][j][2] = 1
            if i - 1 >= 0:
                # 上
                G[i][j][3] = h[i - 1][j]
            else:
                G[i][j][3] = 1

    dist = [[-1 for _ in range(W)] for _ in range(H)]

    dx = [1, 0, -1, 0]  # 斜めも含むならその方向もプラス
    dy = [0, 1, 0, -1]

    bfs((0, 0))

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

    W, H = map(int, input().split())

Python: while True:
    w, h = map(int, input().split())
    if w == 0: break
    goal = (w,h)
    vart = []
    hori = []
    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)]
    while queue:
        p = queue.pop(0)
        x, y = p[0], p[1]
        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))
        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))
        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))
        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))
    print(node[w-1][h-1])

Python: while True:
    w, h = map(int, input().split())
    if w == 0 and h == 0:
        break
    ywalls = [[0]*w for _ in range(h)]
    xwalls = [[0]*w for _ in range(h)]
    for i in range(2*h-1):
        walls = map(int, input().split())
        if i%2==0:
            for j, ele in enumerate(walls):
                ywalls[i//2][j]=ele
        else:
            for j, ele in enumerate(walls):
                xwalls[i//2][j]=ele

    d = [[-1]*w for _ in range(h)]
    sx, sy = 0, 0
    gx, gy = w-1, h-1
    from collections import deque
    q = deque([])
    q.append((sx, sy))
    d[sx][sy] = 0

    while len(q)>0:
        cur = q.popleft()
        #print(cur)
        curx, cury = cur[0], cur[1]
        if curx==gx and cury==gy:
            break
        for dx in range(-1, 2):
            for dy in range(-1, 2):
                if (dx==0 and dy!=0) or (dx!=0 and dy==0):
                    nx, ny = curx+dx, cury+dy
                    if 0<=nx<w and 0<=ny<h and d[ny][nx]==-1:
                        tx, ty = curx, cury
                        if dx==-1:
                            tx -=1
                        elif dy==-1:
                            ty -=1
                        if dx!=0 and ywalls[ty][tx]==0:
                            q.append((nx, ny))
                            d[ny][nx] = d[cury][curx]+1
                        elif dy!=0 and xwalls[ty][tx]==0:
                            q.append((nx, ny))
                            d[ny][nx] = d[cury][curx]+1

    print(d[gy][gx]+1)