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 <vector>
#include <algorithm>
#include <queue>
using namespace std;
const int ALL = ((1 << 4) -1);
///1111 -> NEWS
const int N = (1 << 3);
const int E = (1 << 2);
const int W = (1 << 1);
const int S = 1;
int dx[4] = {0,-1,1,0};
int dy[4] = {1,0,0,-1};
int bfs(vector<vector<int> > &map){
  queue<int> qu_x;
  queue<int> qu_y;
  qu_x.push(0);
  qu_y.push(0);
  vector<vector<int> > ans(map.size()+1,vector<int>(map[0].size()+1,0));
  ans[0][0] = 1;
  while(!qu_x.empty()){
    int x,y;
    x = qu_x.front();qu_x.pop();
    y = qu_y.front();qu_y.pop();
    for(int i = 0;i < 4;i++){
      if((map[x][y] & (1<<i)) == 0){
	if(ans[x+dx[i]][y+dy[i]] == 0){
	  ans[x+dx[i]][y+dy[i]] = ans[x][y]+1;
	  qu_x.push(x+dx[i]);
	  qu_y.push(y+dy[i]);
	}
      }

    }
  }
  return ans[map.size()-2][map[0].size()-2];
  
}
int main(){
  //  cout << (6 & 1) << endl;
  while(1){
    int w,h;
    cin >> w >> h;
    if(w == 0 && h == 0)break;
    vector<vector<int> > map(w+1,vector<int>(h+1,0));
    for(int i = 0;i < h;i++){
      for(int j = 0;j < w-1;j++){
	int tmp;
	cin >> tmp;
	if(j == 0){
	  map[j][i] = (map[j][i] | W);
	}
	if(j == w-2){
	  map[j+1][i] = (map[j+1][i] | E);
	}
	if(i == 0){
	  map[j][i] = (map[j][i] | N);
	  map[j+1][i] = (map[j+1][i] | N);
	}
	if(i == h-1){
	  map[j][i] = (map[j][i] | S);
	  map[j+1][i] = (map[j+1][i] | S);
	}
	if(tmp == 1){
	  map[j][i] = (map[j][i] | E);
	  map[j+1][i] = (map[j+1][i] | W);
	}
      }
      if(i != h-1){
	for(int j = 0;j < w;j++){
	  int tmp;
	  cin >> tmp;
	  if(tmp == 1){
	    map[j][i] =(map[j][i] | S);
	    map[j][i+1] = (map[j][i+1] | N);
	  }
	}
      }
     
    }/*
    cout << endl;
    for(int i = 0;i < h;i++){
      for(int j = 0;j < w;j++){
	if((map[j][i] & N) == N)
	  cout << "N";
	if((map[j][i] &W) == W)
	  cout << "W";
	if((map[j][i] &E)== E)
	  cout << "E";
	if((map[j][i]&S) == S)
	cout << "S";
	cout << "a\t" ;
      }
      cout << endl;
      }*/
    //    cout << "END" << endl;
    //    cout << map[w-1][h-1] << endl;
    //    int ans;
    cout << bfs(map) << endl;
  }
  return 0;
}

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

using namespace std;

// →　↓　←　↑
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
int h, w;
bool maze[32][32][4];
bool past[32][32];


class state {
public:
    int x, y, d;
    state(int a, int b, int c) { x = a; y = b; d = c; }
};


void solve()
{
    bool flag = false;
        
    state s(0, 0, 1);
    queue<state> q;
    q.push(s);
        
    while (!q.empty()) {
        state now = q.front();
        q.pop();
        past[now.y][now.x] = true;
            
        if (now.x == w - 1 && now.y == h - 1) {
            cout << now.d << endl;
            flag = true;
            break;
        }

        for (int i = 0; i < 4; i++) {
            if (maze[now.y][now.x][i])
                continue;
            int nx = now.x + dx[i];
            int ny = now.y + dy[i];

            if (nx < 0 || ny < 0 || nx >= w || ny >= h)
                continue;

            if (past[ny][nx] == false) {
                past[ny][nx] = true;
                q.push(state(nx, ny, now.d + 1));
            }
        }
    }

    if (!flag)
        cout << 0 << endl;
}

int main()
{
    while (cin >> w >> h, w || h) {
        int inp;

        memset(maze, 0, sizeof(maze));
        memset(past, 0, sizeof(past));
        // Input
        for (int y = 0; y < h; y++) {
            for (int x = 0; x < w - 1; x++) {
                cin >> inp;
                if (inp == 0)
                    maze[y][x + 1][2] = maze[y][x][0] = false;
                else
                    maze[y][x + 1][2] = maze[y][x][0] = true;
            }

            if (y < h - 1) 
                for (int x = 0; x < w; x++) {
                    cin >> inp;
                    if (inp == 0)
                        maze[y + 1][x][3] = maze[y][x][1] = false;
                    else
                        maze[y + 1][x][3] = maze[y][x][1] = true;                        
                }
        }

        solve();
    }

    return 0;
}