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<queue>

using namespace std;

	int w,h,a,ans,tx,ty,fg;
	bool map[62][62];
	int lap[62][62];
	
struct Node{
	int x,y,d;
	Node(int a,int b,int c){
		x=a;
		y=b;
		d=c;
	}
};
typedef struct Node node;
static const int dx[]={-1,0,1,0},dy[]={0,-1,0,1};

void sagasu(int,int,int);

int main(){
	//??\????????????????????§??????????????????????????¨????????????????????????????????????
	cin>>w;
	cin>>h;
	
	while(w!=0 || h!=0){
		ans=0;
		for(int lop=0;lop<62;lop++){
			for(int lop2=0;lop2<62;lop2++){
				if(lop==0 || lop==61 || lop2==0 || lop2==61|| lop2==w*2 || lop==h*2){
					map[lop][lop2]=1;
				}else{
					map[lop][lop2]=0;
				}
				lap[lop][lop2]=0;
			}
		}
		fg=0;
		//?????????????????´
		map[0][1]=0;
		map[h*2][w*2-1]=0;
		//??\?????£?????£
		
		for(int lop=0;lop<h*2-1;lop++){
			if(lop%2==0 || lop==0){
				for(int lop2=0;lop2<w-1;lop2++){
					cin>>a;
					if(a==1){
						if(map[lop][lop2*2+2]==0){
							map[lop][lop2*2+2]=1;
						}
						if(map[lop+1][lop2*2+2]==0){
							map[lop+1][lop2*2+2]=1;
						}
						if(map[lop+2][lop2*2+2]==0){
							map[lop+2][lop2*2+2]=1;
						}
					}
				}
			}else{
				for(int lop2=0;lop2<w;lop2++){
					cin>>a;
					if(a==1){
						if(map[lop+1][lop2*2]==0){
							map[lop+1][lop2*2]=1;
						}
						if(map[lop+1][lop2*2+1]==0){
							map[lop+1][lop2*2+1]=1;
						}
						if(map[lop+1][lop2*2+2]==0){
							map[lop+1][lop2*2+2]=1;
						}
					}
				}
			}
		}
		//?£???????????????????????????????????£?????????????????????????
		//?????¨?¨???§??????????????´???????£???????
		
		bool done[62][62]={0};
		queue<node> q;
		q.push(node(1,1,0));
		//??¨??¢?´¢??¨?????\?????????
		
		/*while(q.size()!=0){
			node qq=q.front();
			q.pop();
			
			cout<<qq.x<<' '<<qq.y<<' '<<qq.d<<endl;
			cout<<qq.node.a<<' '<<qq.node.b<<' '<<qq.node.c<<endl;
		}*/
		
		/*
		while(q.size()!=0){
			node qq=q.front();
			q.pop();
			//???????????? ??????????????¶ 1,1,0
			
			if(done[qq.y][qq.x]==0){
				//?£??????????????????????
				done[qq.y][qq.x]=1;
				//??????????????????????£??????????
				
				if(qq.x==w*2-1 && qq.y==h*2-1){
					ans=(qq.d+2)/2;
					break;
				}
				//??´????????????????????¢
				
				//cout<<"aaaa"<<endl;
				for(int lop=0;lop<4;lop++){
					//????????????????????§??????????????\????????\??????
					//??????????¬???????????????§?????????????????????????¢????
					//????????¢???????????´???????£?????????£??????????????§??\???????????????
					tx=dx[lop]+qq.x;
					ty=dy[lop]+qq.y;
					
					if(map[ty][tx]==0){
						q.push(node(tx,ty,qq.d+1));
					}
					
				}
			}
			//?????????????????´???0??????????????????
		}*/
		
		//sagasu(0,1,1);
		//cout<<ans/2<<endl;
		
		//??????????????¨????????\????????????????????????????????????????????????????????????
		//??????????????????????????§???????????????
		//?????????????????§?????°??¢??°??§?????£?????????
		
		/*for(int lop=0;lop<62;lop++){
			for(int lop2=0;lop2<62;lop2++){
				cout<<map[lop][lop2]<<' ';
			}
			cout<<endl;
		}*/
		sagasu(0,1,1);
		cout<<ans/2<<endl;
		
		cin>>w;
		cin>>h;
	}
	
	return 0;
}


void sagasu(int xx,int yy,int kazu){
	//cout<<"aa "<<xx<<"  "<<yy<<"  "<<kazu<<endl;
	
	if(map[xx][yy]==1 || lap[xx][yy]!=0){
		return;
	}
	map[xx][yy]=1;
	if(lap[xx][yy]>kazu || lap[xx][yy]==0){
		lap[xx][yy]=kazu;
		kazu++;
	}else{
		kazu=lap[xx][yy];
	}
	
	if(xx==h*2 && w*2-1==yy){
		fg=1;
		ans=lap[xx][yy];
		return;
	}else if(fg==1){
		return;
	}
	
	if(/*xx+1<h*2 &&*/ map[xx+1][yy]==0){
		sagasu(xx+1,yy,kazu);
	}
	if(/*yy+1<w*2 && */map[xx][yy+1]==0){
		sagasu(xx,yy+1,kazu);
	}
	if(xx-1>0 && map[xx-1][yy]==0){
		sagasu(xx-1,yy,kazu);
	}
	if(yy-1>0 && map[xx][yy-1]==0){
		sagasu(xx,yy-1,kazu);
	}
		return;
}