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;

const int sz_max = 30;
const int INF = 2140000000;

int dx[] = {
	-1, 0, 1, 0
};
int dy[] = {
	0, 1, 0, -1
};

struct p{
	int d;
	bool dir[4];
};
struct place{
	int y;
	int x;
};

p points[sz_max][sz_max];

void bfs(int i, int j){
	queue<place> q;
	place pl;
	pl.x = j;
	pl.y = i;
	q.push(pl);
	while(!q.empty()){
		place point = q.front();
		int y = point.y;
		int x = point.x;
		q.pop();
		for(int k = 0; k < 4; k++){
			if(points[y][x].dir[k])
				if(points[y+dy[k]][x+dx[k]].d == INF ||
					points[y][x].d + 1 < points[y+dy[k]][x+dx[k]].d)
				{
					points[y+dy[k]][x+dx[k]].d = points[y][x].d + 1;
					pl.y = y+dy[k];
					pl.x = x+dx[k];
					q.push(pl);
				}
		}
	}
}

int main(){
	int w, h;
	while(cin >> w >> h){
		if(w == 0 && h == 0) break;
		for (int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				points[i][j].d = INF;
				for(int k = 0; k < 4; k++){
					points[i][j].dir[k] = false;
				}
			}
		}
		for(int i = 0; i < h; i++){
			char c;
			for(int j = 0; j < w - 1; j++){
				cin >> c;
				if(c == '0'){
					points[i][j].dir[2] = true;
					points[i][j+1].dir[0] = true;
				}
			}
			if(i == h - 1) break;
			for(int j = 0; j < w; j++){
				cin >> c;
				if(c == '0'){
					points[i][j].dir[1] = true;
					points[i+1][j].dir[3] = true;
				}
			}
		}
		points[0][0].d = 1;
		bfs(0,0);
		if(points[h-1][w-1].d == INF) cout << 0 << endl;
		else cout << points[h-1][w-1].d << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<queue>

using namespace std;

int main(){
  int w,h;
  char maze[50][50];

  cin>>w>>h;
  while(w!=0 && h!=0){
    //“?—???????'#'??'.'???????????H?????¬
    for(int i=0;i<2*w+1;i++){
      maze[0][i] = '#';
    }
    maze[0][1] = 's';//start

    for(int i=1;i<h*2;i++){
      int c;
      if(i%2 != 0){//?c????????
	maze[i][0] = '#';//???¶????
	for(int j=1;j<w*2;j++){
   if(j %2 ==0){
     cin>>c;
     if(c==0){
       maze[i][j] = '.';
     }else{
	      maze[i][j] = '#';//??‰E????
	    }
	  }else{
     maze[i][j] = '.';
   }
 }
 maze[i][w*2] = '#';
      }else{//‰?????????
       maze[i][0] = '#';
       for(int j=1;j<w*2;j++){
         if(j%2 == 0){
           maze[i][j] = '#';
         }else{
           cin>>c;
           if(c==0){
             maze[i][j] = '.';
           }else{
             maze[i][j] = '#';
           }
         }

       }
       maze[i][w*2] = '#';
     }
   }
   
   for(int i=0;i<2*w+1;i++){
    maze[h*2][i] = '#';
  }
    maze[h*2][w*2-1] = 'g';//goal
    

    int ans = 0;
    int next[4][2] = {{1,0},{-1,0},{0,1},{0,-1}};
    queue<pair<pair<int,int>,int> >  que;
    que.push(make_pair(make_pair(0,1),0));

    while(!que.empty()){

      pair<int,int> now = que.front().first;
      int count = que.front().second;
      que.pop();
      
      if(maze[now.first][now.second] == 'g'){
       ans = count;

       break;
     }
     maze[now.first][now.second] ='#';

     for(int i=0;i<4;i++){
       int ny = now.first + next[i][0];
       int nx = now.second + next[i][1];
       if(ny>=0 && nx>=0 && ny<=h*2 && nx<=w*2 && maze[ny][nx] != '#'){
         que.push(make_pair(make_pair(ny,nx),count+1));
       }
     }

   }

   cout<<ans/2<<endl;
   cin>>w>>h;
 }

 return 0;
}