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<bits/stdc++.h>
#define F first
#define S second
#define INF 1e9
using namespace std;
typedef pair<int,int> P;
int w,h;
int mp[31][31];
bool mpj[31][31][4];
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int bfs(int y,int x){
    mp[y][x]=1;
    
    queue<P> que;
    que.push(make_pair(y,x));
    while(!que.empty()){
        P p = que.front();
        que.pop();
        for(int i=0;i<4;i++){
            int nx = p.S + dx[i], ny = p.F + dy[i];
            if(nx < 0 || nx > w-1 || ny < 0 || ny > h-1 || mpj[p.F][p.S][i]==false) continue;
            if(mp[ny][nx]>mp[p.F][p.S]+1){
                mp[ny][nx]=mp[p.F][p.S]+1;
                que.push(make_pair(ny,nx));
            }
        }
    }
    
    if(mp[h-1][w-1]==INF) return 0;
    else return mp[h-1][w-1];
    
}
int main(){
    while(cin>>w>>h,w || h){
        
        for(int i=0;i<h;i++)
            for(int j=0;j<w;j++)
                for(int k=0;k<4;k++) mpj[i][j][k]=true;
        
        for(int i=0;i<h;i++)
            for(int j=0;j<w;j++) mp[i][j]=INF;
        
        int kabe;
        for(int i=0;i<h;i++){
            for(int j=0;j<w-1;j++){
                cin>>kabe;
                if(kabe){
                    mpj[i][j][0]=false;
                    mpj[i][j+1][2]=false;
                }
            }
            if(i!=h-1){
                for(int j=0;j<w;j++){
                    cin>>kabe;
                    if(kabe){
                        mpj[i][j][1]=false;
                        mpj[i+1][j][3]=false;
                    }
                }
            }
        }
        
        cout<<bfs(0,0)<<endl;
    }
    
    return 0;
}

C++: #include<iostream>
#define MAX 10000000
#define Rep(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) Rep(i,0,a)
using namespace std;
int sum,u[50][50][8],v[50][50];
int w,h;
int dx[]={0,0,-1,1},dy[]={1,-1,0,0},d[50][50];
void func(int x,int y,int now){
		d[y][x]=now;
	if(x!=w-1||y!=h-1){
		rep(i,4)
		if(u[y][x][i]==1&&d[y+dy[i]][x+dx[i]]>now+1)
		func(x+dx[i],y+dy[i],now+1);
	}
}
int main(){
	int box[50][50];
	while(cin>>w>>h,w||h){
		rep(i,2*h-1)
		rep(j,w-1+i%2)
		cin>>box[i][j];
		//1
	   //2 3
		//0
		rep(i,h)
		rep(j,w){
			d[i][j]=MAX;
			if(j==0)
				u[i][0][2]=0;
			else {
				if(box[2*i][j-1]==1)
					u[i][j][2]=0;
				else u[i][j][2]=1;
			}
			if(i==0)
				u[0][j][1]=0;
			else {
				if(box[2*i-1][j]==1)
					u[i][j][1]=0;
				else u[i][j][1]=1;
			}
			if(i==h-1)
				u[h-1][j][0]=0;
			else {
				if(box[2*i+1][j]==1)
					u[i][j][0]=0;
				else u[i][j][0]=1;
			}
			if(j==w-1)
				u[i][w-1][3]=0;
			else {
				if(box[2*i][j]==1)
					u[i][j][3]=0;
				else u[i][j][3]=1;
			}
		}
	func(0,0,1);
	if(d[h-1][w-1]==MAX)
		cout<<'0';
	else cout<<d[h-1][w-1];
	cout<<endl;
	}
	return 0;
}