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<cstdio>
#include<string>
#include<queue>

using namespace std;
int bfs(int x,int y);
int w,h;
int i,j;
int dy[4] = {1,0,-1,0}, dx[4] = {0,-1,0,1};
string map[100];
int dis[100][100];
queue<pair<int,int> > q;
int main(){
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    w = 2*w -1;
    h = 2*h -1;
    cin.ignore();
    for(i = 0;i < h;i++){
      getline(cin,map[i]);
    }
    bfs(0,0);
    if(dis[h-1][w-1] > 0){
    cout << dis[h-1][w-1] +1<<endl;
    }else{
      cout << 0 <<endl;
    }
  }
  return 0;
}

int bfs(int x,int y){
  int k;
  pair<int,int> g;
  pair<int,int> tmp;
  g.first = w-1;
  g.second = h -1;
  for(k = 0;k < 4;k++){
    if(y +  2*dy[k] >-1 && y + 2*dy[k] < h && x + 2*dx[k] < w && x + 2*dx[k] > -1){
      if(map[y + dy[k]][x + dx[k]] == '0'){
	map[y + dy[k]][x + dx[k]] ='1';
	tmp.second = x + 2*dx[k];
	tmp.first = y +2*dy[k];
	q.push(tmp);
	dis[y + 2*dy[k]][x + 2*dx[k]] = dis[y][x] + 1;
      }
    }
  }
  while(q.size() != 0){
    tmp = q.front();
    q.pop();
    if(tmp == g) break;
    bfs(tmp.second,tmp.first);
  }
  return 0;
}

C++: #include <iostream>
#include <cstring>
#include <queue>
#include <utility>
using namespace std;

#define SIZE 30

const int dy[4] = {-1, 0, 1, 0};
const int dx[4] = {0, 1, 0, -1};
int w, h;
bool walls[SIZE + 1][SIZE + 1][4];
int maze[SIZE + 1][SIZE + 1];

void run() {
    maze[0][0] = 1;
    queue<pair<int, int> > q;
    q.push(make_pair(0, 0));
    while (q.empty() == false) {
        int y = q.front().first, x = q.front().second;
        q.pop();
        for (int i = 0; i < 4; i++) {
            int ny = y + dy[i], nx = x + dx[i];
            if (0 <= ny && ny < h && 0 <= nx && nx < w && walls[y][x][i] == 0
                && (maze[ny][nx] == 0 || maze[y][x] + 1 < maze[ny][nx])) {
                maze[ny][nx] = maze[y][x] + 1;
                q.push(make_pair(ny, nx));
            }
        }
    }
}

int main() {
    while (true) {
        cin >> w >> h;
        if ((w | h) == 0) {
            break;
        }
        memset(maze, 0, sizeof(maze));
        memset(walls, false, sizeof(walls));
        for (int y = 0; y < h; y++) {
            int temp;
            for (int x = 0; x < w - 1; x++) {
                cin >> temp;
                walls[y][x][1] = walls[y][x + 1][3] = temp;
            }
            if (y < h - 1) {
                for (int x = 0; x < w; x++) {
                    cin >> temp;
                    walls[y][x][2] = walls[y + 1][x][0] = temp;
                }
            }
        }
        run();
        cout << maze[h - 1][w - 1] << endl;
    }
}

C++: #include<iostream>
#include<string.h>
#include<queue>

using namespace std;

typedef pair<int,int> P;

bool wall[30][30][4];
int dis[30][30];
int dx[4] = {1,0,-1,0},dy[4] = {0,-1,0,1};

int main(){
	while(true){
		int n,m;
		cin >> n >> m;
		
		if(n == 0 && m == 0) break;
		
		memset(wall,0,sizeof(wall));
		memset(dis,0,sizeof(dis));
		
		for(int i = 0;i < (m * 2)-1;i++){
			if(i % 2 == 0){
				for(int j = 0;j < n-1;j++){
					int w;
					cin >> w;
					if(w == 1){
						wall[i/2][j][0] = 1;
						wall[i/2][j+1][2] = 1;
					}
				}
			}else{
				for(int j = 0;j < n;j++){
					int w;
					cin >> w;
					if(w == 1){
						wall[i/2][j][3] = 1;
						wall[(i/2)+1][j][1] = 1;
					}
				}
			}
		}
		
		queue<P> que;
		que.push(P(0,0));
		dis[0][0] = 1;
		
		while(que.size()){
			P p = que.front(); que.pop();
			if(p.first == (n-1) && p.second == (m-1)) break;
			for(int i = 0;i < 4;i++){
				int nx = p.first + dx[i],ny = p.second + dy[i];
				if(0 <= nx && nx < n && 0 <= ny && ny < m && dis[ny][nx] == 0 && wall[p.second][p.first][i] == 0){
					que.push(P(nx,ny));
					dis[ny][nx] = dis[p.second][p.first] + 1;
				}
			}
		}
		
		if(dis[m-1][n-1] == 0){
			cout << 0 << endl;
		}else{
			cout << dis[m-1][n-1] << endl;
		}
	}
	return 0;
}