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)
}

C++: #include <iostream>
#include <cstdio>
#include <map>
#include <queue>

using namespace std;

const int INF = 10000000;
int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};

typedef pair<int, int> P;


//void search(int **d, int **data, int x, int y, int w, int h, int temp_dis, int &distance, bool &result);

int bfs(int **d, int **data, int x, int y, int w, int h){
	queue<P> que;
	int sx = 1, sy = 1;
	int gx = (2*w-1), gy = (2*h+1);
	//すべての点をINFで初期化
	for (int i = 0; i < (2*h+3); ++i){
		for (int j = 0; j < (2*w+1); ++j){
			d[i][j] = INF;
		}
	}
	que.push(P(sx,sy));
	d[sy][sx] = 0;

	while (que.size()){
		P p = que.front();
		que.pop();
		if ((p.first == gx) && (p.second == gy)){
			break;
		}

		//移動4方向のループ
		for (int i=0; i<4; ++i){
			int nx = p.first + dx[i];
			int ny = p.second + dy[i];

			if ((1<=nx) && (nx<(2*w)) && (1<=ny) && (ny<(2*h+2)) && (data[ny][nx]!=1) && (d[ny][nx]==INF)){
				que.push(P(nx, ny));
				d[ny][nx] = d[p.second][p.first] + 1;
			}
		}
	}
	return d[2*h+1][2*w-1];
}

int main(void){
	int w, h;
	while (cin >> w >> h){
		if ((w == 0) && (h == 0)){
			return 0;
		}
		int **data = new int*[2*h+1+2];
		int **d = new int*[2*h+1+2];
		for (int i=0; i<(2*h+1+2); ++i){
			data[i] = new int[2*w+1];
			d[i] = new int [2*w+1];
		}

		for (int i=0; i<(2*h+1+2); ++i){
			for (int j=0; j<(2*w+1); ++j){
				if ((i == 0) || (i == (2*h+2))){
					data[i][j] = 1;
					d[i][j] = 1;
				}
				else if (i == 1){//start
					if (j == 1){
						data[i][j] = 0;
						d[i][j] = 0;
					}
					else{
						data[i][j] = 1;
						d[i][j] = 1;
					}
				}
				else if (i == (2*h+1)){ //goal
					if (j == (2*w-1)){
						data[i][j] = 0;
						d[i][j] = 0;
					}
					else{
						data[i][j] = 1;
						d[i][j] = 1;
					}
				}
				else{
					if ((j == 0) || (j == (2*w))){//border
						data[i][j] = 1;
						d[i][j] = 1;
					}
					else{
						if (i % 2 == 0){
							if (j % 2 == 1){
								data[i][j] = 0;
								d[i][j] = 0;
							}
							else{
								char c;
								c = getchar();
								cin >> data[i][j];
								if (data[i][j] == 0){
									d[i][j] = 0;
								}
								else{
									d[i][j] = 1;
								}
							}
						}
						else{
							if (j % 2 == 0){
								data[i][j] = 1;
								d[i][j] = 1;
							}
							else{
								cin >> data[i][j];
								if (data[i][j] == 0){
									d[i][j] = 0;
								}
								else{
									d[i][j] = 1;
								}
							}
						}
					}
				}
			}
		}
		
		int distance = 0;
		bool find = false;
		//search(d, data, 1, 1, w, h, 0, distance, find);
		distance = bfs(d, data, 1, 1, 2, h);
		cout << (distance/2) << endl;
		/*
		for (int i=0; i<(2*h+3); ++i){
			for (int j=0; j<(2*w+1); ++j){
				if (data[i][j] == 1){
					cout << "*";
				}
				else{
					cout << "-";
				}
			}
			cout << endl;
		}
*/
		for (int i=0; i<(2*h+3); ++i){
			delete[] data[i];
			delete[] d[i];
		}
		delete [] data;
		delete [] d;
		/*cout << "hoge" << endl;*/
	}
	
	return 0;
}

//
//void search(int **d, int **data, int x, int y, int w, int h, int temp_dis, int &distance, bool &result){
//	d[x][y] = 1;
//	if ((x == (2*w-1)) && (y == (2*h+1))){
//		distance = temp_dis;
//		result = true;
//		return;
//	}
//	else{
//		if ((d[y][x+1] == 1) && (d[y][x-1] == 1) && (d[y+1][x] == 1) && (d[y-1][x] == 1)){
//			distance = 0;
//			result = false;
//			return;
//		}
//	}
//	if ((data[y][x+1] == 0) && (d[y][x+1] == 0)){
//		search(d, data, (x+1), y, w, h, (++temp_dis), distance, result);
//	}
//	if ((data[y+1][x] == 0) && (d[y+1][x] == 0)){
//		search(d, data, x, (y+1), w, h, (++temp_dis), distance, result);
//	}
//	if ((data[y][x-1] == 0) && (d[y][x-1] == 0)){
//		search(d, data, (x-1), y, w, h, (++temp_dis), distance, result);
//	}
//	if ((data[y-1][x] == 0) && (d[y-1][x] == 0)){
//		search(d, data, x, (y-1), w, h, (++temp_dis), distance, result);
//	}
//}