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<string>
#include<vector>
#include<utility>
#include<queue>
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<complex>
#define INF 2147483647
#define llINF 9223372036854775807
#define pb push_back
#define mp make_pair 
#define F first
#define S second
#define ll long long

using namespace std;
int main(){
  int w,h;
  while(cin>>w>>h,w+h){
    bool Map[h][w]={};
    pair<int,int> uMap[h][w][2]={};
    pair<int,int> wMap[h][w][2]={};
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	for(int k=0;k<2;k++){
	  uMap[i][j][k]=mp(-1,-1);
	  wMap[i][j][k]=mp(-1,-1);
	}
      }
    }
    for(int i=0;i<2*h-1;i++){
      if(i%2==0){
	for(int j=1;j<w;j++){
	  int aa;
	  cin>>aa;
	  if(aa){
	    int point=0;
	    if(uMap[i/2][j][0].F>=0)point++;
	    uMap[i/2][j][point]=mp(i/2,j-1);
	    point =0;
	    if(uMap[i/2][j-1][0].F>=0)point++;
	    uMap[i/2][j-1][point]=mp(i/2,j);
	  }
	}
      }else{
	for(int j=0;j<w;j++){
	  int aa;cin>>aa;
	  if(aa){
	    int point=0;
	    if(wMap[(i/2)+1][j][0].F>=0)point++;
	    wMap[(i/2)+1][j][point]=mp(i/2,j);
	    point=0;
	    if(wMap[i/2][j][0].F>=0)point++;
	    wMap[(i/2)][j][point]=mp((i/2)+1,j);
	  }
	}
      }
    }
    Map[0][0]=true;
    queue<pair<pair<int,int>,int > >que;
    que.push(mp(mp(0,0),0));
    int ans=-1;
    while(!que.empty()){
      pair<int,int> now=mp(que.front().F.F,que.front().F.S);
      int num=que.front().S;
      if(now.F==h-1&&now.S==w-1){
	//cout<<now.F<<" "<<now.S<<endl;
	ans=num;break;
      }
      que.pop();
      int vx[4]={0,1,0,-1};int vy[4]={1,0,-1,0};
      for(int i=0;i<4;i++){
	int a=now.F+vx[i],b=now.S+vy[i];
	if(i%2){
	  if((a>=0&&a<h&&b>=0&&b<w)&&(!(wMap[a][b][0].F==now.F&&wMap[a][b][0].S==now.S))&&(!(wMap[a][b][1].F==now.F&&wMap[a][b][1].S==now.S))&&(!Map[a][b])){
	    que.push(mp(mp(a,b),num+1));
	    Map[a][b]=true;
	  }
	}else{
	  if((a>=0&&a<h&&b>=0&&b<w)&&(!(uMap[a][b][0].F==now.F&&uMap[a][b][0].S==now.S))&&(!(uMap[a][b][1].F==now.F&&uMap[a][b][1].S==now.S))&&(!Map[a][b])){
	    que.push(mp(mp(a,b),num+1));
	    Map[a][b]=true;
	  }
	}
      }
    }
    cout<<ans+1<<endl;
  }
  return 0;
}

C++: //Amaizing Mazes
#include<bits/stdc++.h>
using namespace std;

#define INF 100000
//???,???,???,???
int dx[4]={-1, 0, 1, 0}, dy[4]={0, 1, 0, -1};
typedef struct DIR{
  int cango[4];
  int d;
}dir;

int w, h;

int main(){
    while(cin>>w>>h, !(w==0&&h==0)){
    dir a[h][w];
    //??\???
    for(int i=0; i<h*2-1; i++){
      if(i%2==0){
	for(int j=0; j<w-1; j++){//?¨???????
	  int tmp;
	  cin>>tmp;
	  a[i/2][j].cango[1]=tmp;
	  a[i/2][j+1].cango[3]=tmp;
	}
      }
      else{
	for(int j=0; j<w; j++){//?????????
	  int tmp;
	  cin>>tmp;
	  a[i/2][j].cango[2]=tmp;
	  a[i/2+1][j].cango[0]=tmp;
	}
      }
    }
    for(int i=0; i<h; i++)
      for(int j=0; j<w; j++)
	a[i][j].d=INF;
    a[0][0].d=0;
    queue< pair<int, int> > q;
    q.push(pair<int, int>(0, 0));
    bool flag=false;
    while(!q.empty()){
      pair<int, int> now=q.front(); q.pop();
      if(now.first==h-1 && now.second==w-1){
	flag=true;//??´???????????§??????????????????
	break;
      }
      for(int i=0; i<4; i++){
	int nx=now.first+dx[i], ny=now.second+dy[i];
	if(0<=nx && nx<h && 0<=ny && ny<w && a[now.first][now.second].cango[i]==0 && a[nx][ny].d==INF){
	  a[nx][ny].d=a[now.first][now.second].d+1;
	  q.push(pair<int, int>(nx, ny));
	  //printf("push x=%d, y=%d\n", nx, ny);
	}
      }
    }
    if(flag)cout<<a[h-1][w-1].d+1<<endl;
    else cout<<"0"<<endl;
    }
  return 0;
}