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: X = [1,-1,0,0]
Y = [0,0,1,-1]
B = [1,2,4,8]

while 1:
    w, h = list(map(int,input().split()))
    if w == 0:break

    _map = [[0 for i in range(w)] for i in range(h)]
    dp = [[99999999 for i in range(w)] for i in range(h)]

    for i in range(h*2-1):
        for j,v in enumerate(list(map(int,input().split()))):
            if v == 0:continue
            if i % 2 == 0 :
                _map[i // 2][j] += B[0]
                if j+1 < w:
                    _map[i // 2][j+1] += B[1]
            else:
                _map[i // 2][j] += B[2]
                if (i // 2) + 1 < h:
                    _map[(i // 2)+1][j] += B[3]
    lst = [(1,0,0)]
    dp[0][0] = 1
    res = 0

    # print(_map)
    while len(lst) > 0:
        spam = lst.pop(0)
        for i in range(4):
            x = spam[2] + X[i]
            y = spam[1] + Y[i]
            if x < 0 or y < 0 or x >= w or y >= h or  \
                B[i] & _map[spam[1]][spam[2]] != 0 or dp[y][x] <= spam[0] + 1:
                continue
            if x+1 == w and y+1 == h:
                res = spam[0] + 1
                break
            lst.append((spam[0] + 1, y, x))
            dp[y][x] = spam[0] + 1
        if res > 0:break
        lst.sort()

    print(res)

Python: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1166&lang=jp
AC
"""
import sys
from sys import stdin
from collections import deque
input = stdin.readline


def bfs(maze, w, h):
    # ????????????????§????????????´????????§?¨??????????
    dy = [-1, 1, 0, 0]
    dx = [0, 0, -1, 1]

    # ??????????????°???(S)??¨??´????????°???(G)?????????
    sx = 0                   #  ??????????????°????????§?¨?
    sy = 0
    gx = w - 1               #  ??´????????°????????§?¨?
    gy = h - 1

    d = [[float('inf')] * w for _ in range(h)] #  ??????????????°?????????????????¢???INF??§?????????
    Q = deque()
    Q.append((sx, sy))
    d[sy][sx] = 0
    while Q:
        cx, cy = Q.popleft()        #  ?????¨??°?????§?¨?
        if cx == gx and cy == gy:
            return d[gy][gx] + 1    #  ?????????????????????????????§????????°????±?????????????????????????????????§????????£?????§????????°+1?????????
        for i in range(len(dx)):
            nx = cx + dx[i]
            ny = cy + dy[i]
            #  ?§????????????§???????????? ?????? ??¢?????¢?´¢?????§???????????°??????????????§?????¢?´¢????¶???????
            if is_passable(maze, w, h, cx, cy, dx[i], dy[i]) and d[ny][nx] == float('inf'):
                Q.append((nx, ny))
                d[ny][nx] = d[cy][cx] + 1
    return 0                    #  ??¨??¢?´¢??????????????´???????????§???????????????????????£???


def is_passable(maze, w, h, cx, cy, dx, dy):
    # ?§????????????°????????????????????????????????? ?????? ??????????£???????????????¨ ????¢????
    if not 0 <= (cx + dx) < w:
        return False
    if not 0 <= (cy + dy) < h:
        return False
    if dy == -1:                #  up
        return True if maze[cy*2-1][cx] == 0 else False
    if dy == 1:                 #  down
        return True if maze[cy*2+1][cx] == 0 else False
    if dx == -1:                #  left
        return True if maze[cy*2][cx-1] == 0 else False
    if dx == 1:                 #  right
        return True if maze[cy*2][cx] == 0 else False


def solve(maze, w, h):
    return bfs(maze, w, h)


def main(args):
    while True:
        w, h = map(int, input().split(' '))
        if w == 0 and h == 0:
            break

        maze = []
        for d in range(h*2-1):
            maze.append([int(x) for x in input().strip().split(' ')])

        res = solve(maze, w, h)
        print(res)


if __name__ == '__main__':
    main(sys.argv[1:])