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>
using namespace std;

int w,h;

int get_index(int x,int y){
  return x + y * w;
}

void add_edge(vector<vector<int>> &maze,int x1,int y1,int x2,int y2){
  const int a = get_index(x1,y1);
  const int b = get_index(x2,y2);
  maze[a].emplace_back(b);
  maze[b].emplace_back(a);
}

int bfs(int s,int g,vector<vector<int>> &maze){
  const int n = maze.size();
  vector<int> d(n,-1);
  d[s] = 1;
  queue<int> q;
  q.push(s);
  while(!q.empty()){
    const int now = q.front(); q.pop();

    if(now == g) return d[now];

    for(const auto &to : maze[now]){
      if(d[to] == -1){
        d[to] = d[now] + 1;
        q.push(to);
      }
    }
  }
  return -1;
}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  while(cin>>w>>h&&w){
    vector<vector<int>> maze(w*h);

    for(int i=0;i<h;++i){
      for(int j=0;j<w-1;++j){
        int wall; cin>>wall;
        if(!wall)
          add_edge(maze,j,i,j+1,i);
      }
      if(i==h-1) break;
      for(int j=0;j<w;++j){
        int wall; cin>>wall;
        if(!wall){
          add_edge(maze,j,i,j,i+1);
        }
      }
    }

    const int ans = bfs(get_index(0,0),get_index(w-1,h-1),maze);
    ans == -1 ? cout<<0<<endl : cout<<ans<<endl;
  }

  return EXIT_SUCCESS; 
}

C++: #include <iostream>
#include <queue>
#include <vector>
using namespace std;
int w,h;
char map[200][200];
class Node{
public:
	int x,y;
	int c;
	Node(int _x,int _y,int _c):x(_x),y(_y),c(_c){

	}
};
void show(){
	for(int i=0;i<h*2-1;i++){
		for(int j=0;j<w*2-1;j++)cout<<map[i][j];
		cout<<endl;
	}
	cout<<endl;
}
bool visited[200][200];
int dx[]={1,0,-1,0};
int dy[]={0,-1,0,1};
int bfs(){
	for(int i=0;i<100;i++)fill(visited[i],visited[i]+100,false);
	queue<Node> q;
	q.push(Node(0,0,1));
	visited[0][0]=true;
	int gw=2*w-2;
	int gh=2*h-2;
	while(!q.empty()){
		Node cur=q.front();q.pop();
//		cout<<"("<<cur.x<<","<<cur.y<<")"<<endl;
		map[cur.y][cur.x]='1';
//		show();
		if(cur.x==gw&&cur.y==gh)return cur.c;
		for(int i=0;i<4;i++){
			int nx=cur.x+dx[i];
			int ny=cur.y+dy[i];
//			cout<<"next("<<nx<<","<<ny<<")"<<endl;
			if(nx<0||ny<0||nx>gw||ny>gh||map[ny][nx]=='1')continue;
			nx=nx+dx[i];
			ny=ny+dy[i];
			if(nx<0||ny<0||nx>gw||ny>gh||map[ny][nx]=='1')continue;
//			map[ny+dy[i]][nx+dx[i]]=='1')continue;
			if(visited[ny][nx])continue;
			visited[ny][nx]=true;
			q.push(Node(nx,ny,cur.c+1));
		}
	}
	return 0;
}
void solve(){
	cout<<bfs()<<endl;
}
int main(){
	while(cin>>w>>h&&(w||h)){
		for(int i=0;i<100;i++)for(int j=0;j<100;j++)map[i][j]='0';
		int hline=h*2-1;
		for(int i=0;i<hline;i++){
			if(i%2){
				for(int j=0;j<w;j++)cin>>map[i][2*j];
			}
			else {
				for(int j=0;j<w-1;j++)cin>>map[i][1+2*j];

			}
		}
//		show();
		solve();
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int h,w;
bool vis[50][50];
bool canw[50][50];
bool canh[50][50];
int qx[100000],qy[100000],ql[100000];
int head,tail;
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
int ans;
bool bend;
void BFS(int x,int y,int len){
	if(x==w-1&&y==h-1){
		ans=len;
		bend=true;
	}
	for(int i=0;i<4;i++){
		if(x+dx[i]>=0&&x+dx[i]<w&&y+dy[i]>=0&&y+dy[i]<h){
			bool ok=false;
			if(i==0&&!canh[y][x])ok=true;
			if(i==1&&!canw[y][x])ok=true;
			if(i==2&&!canh[y-1][x])ok=true;
			if(i==3&&!canw[y][x-1])ok=true;
			if(ok&&vis[y+dy[i]][x+dx[i]]==false){
				vis[y+dy[i]][x+dx[i]]=true;
				qx[tail]=x+dx[i],qy[tail]=y+dy[i],ql[tail]=len+1;
				tail++;
			}
		}
	}
}
int main(){
	while(true){
	cin>>w>>h;
	if(w==0&&h==0)break;
	for(int i=0;i<h-1;i++){
		for(int j=0;j<w-1;j++)cin>>canw[i][j];
		for(int j=0;j<w;j++)cin>>canh[i][j];
	}
	for(int j=0;j<w-1;j++)cin>>canw[h-1][j];

	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			vis[i][j]=false;
		}
	}
	qx[0]=0,qy[0]=0,ql[0]=1;
	head=0,tail=1;
	ans=0;
	bend=false;
	while(true){
		if(head==tail)break;
		BFS(qx[head],qy[head],ql[head]);
		if(bend)break;
		head++;
	}
	cout<<ans<<endl;
	}
	return 0;
}