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 <stdio.h>
#include <string.h>
#include <queue>
#include <utility>
using namespace std;
#define rep(i, n) for(int i=0; i<(int)(n); i++)

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

int H, W, wall[32][32][4], ds[32][32];

int solve() {
    typedef pair<int, int> P;
    memset(ds, -1, sizeof(ds));
    queue<P> q;
    q.push(P(0, 0));
    ds[0][0] = 1;
    while(!q.empty()) {
        pair<int, int> vv(q.front());
        q.pop();
        const int x = vv.first;
        const int y = vv.second;
        if(x==H-1 && y==W-1) return ds[x][y];
        rep(d, 4) if(wall[x][y][d]==0) {
            const int nx = x+dx[d], ny = y+dy[d];
            if(ds[nx][ny]==-1) {
                ds[nx][ny] = ds[x][y]+1;
                q.push(P(nx, ny));
            }
        }
    }
    return 0;
}

int main() {
    for(;;) {
        scanf("%d%d", &W, &H);
        if(W==0 && H==0) return 0;
        memset(wall, -1, sizeof(wall));
        rep(i, 2*H-1) {
            const int x = i/2;
            if(i%2==0) {
                rep(j, W-1) {
                    int a;
                    scanf("%d", &a);
                    wall[x][j][1] = wall[x][j+1][3] = a;
                }
            }
            else {
                rep(j, W) {
                    int a;
                    scanf("%d", &a);
                    wall[x][j][0] = wall[x+1][j][2] = a;
                }
            }
        }
        printf("%d\n", solve());
    }
}

C++: #include <iostream>
using namespace std;
#define debug 0

int d[202][202];
int m[202][202];
int queX[40806];
int queY[40806];

int w,h;
int ans;

void draw(){
	if(debug){
		for(int i=0;i<=h*2;i++){
			for(int j=0;j<=w*2;j++){
				if(d[j][i]==1)cout<<"#";
				else cout<<" ";
			}
			cout<<endl;
		}
		cout<<endl;
	}
}

void push(int X,int Y,int num){
	m[X][Y]=num;
	queX[queX[0]+1]=X;
	queY[queY[0]+1]=Y;
	queY[0]++;
	queX[0]++;
}
void pop(){
	queX[1]++;
	queY[1]++;
}
void reset(){
	for(int i=0;i<=h*2;i++)for(int j=0;j<=w*2;j++)d[j][i]=0;
	for(int i=0;i<=h*2;i++)for(int j=0;j<=w*2;j++)m[j][i]=-1;
	for(int i=0;i<=w*2;i++)d[i][0]=d[i][h*2]=1;
	for(int i=0;i<=h*2;i++)d[0][i]=d[w*2][i]=1;
	for(int i=2;i<=h*2-2;i+=2)for(int j=2;j<=w*2-2;j+=2)d[j][i]=1;
	queX[0]=queY[0]=1;//2から追加/最後に追加した場所=1
	queX[1]=queY[1]=1;//2を放出/最後に放出した場所=1
	push(2*w-1,2*h-1,0);
}
void scan(){
	for(int i=1;i<=h*2-1;i++){
		if(i%2)for(int j=1;j<w;j++)cin>>d[j*2][i];
		else for(int j=1;j<=w;j++)cin>>d[j*2-1][i];
	}
	draw();
}
void cal(){
	int PX[4]={0,1,0,-1};
	int PY[4]={1,0,-1,0};
	
	for(;queX[0]>queX[1];pop()){
		//cout<<"*"<<queX[queX[1]+1]<<" "<<queY[queY[1]+1]<<" *"<<queX[0]<<" "<<queY[1]<<endl;
		for(int i=0;i<4;i++){
			if(d[queX[queX[1]+1]+PX[i]][queY[queY[1]+1]+PY[i]]==0){
				if(m[queX[queX[1]+1]+PX[i]][queY[queY[1]+1]+PY[i]]<0)push(queX[queX[1]+1]+PX[i],queY[queY[1]+1]+PY[i],m[queX[queX[1]+1]][queY[queY[1]+1]]+1);
			}
		}
	}
}
int main(){	
	while(cin>>w>>h,w){
		reset();
		scan();
		cal();
		if(m[1][1]<0)cout<<0<<endl;
		else cout<<m[1][1]/2+1<<endl;
	}
	
	return 0;
}