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;

int mem[60][30], H, W, dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};
int d[30][30];
int main()
{
loop:
  for(int i = 0; i < 30; i++)
    for(int j = 0; j < 30; j++)
      d[i][j] = 0;
  
  cin >> W >> H;
  if(!W)
    return 0;
  for(int i = 0; i < H * 2 - 1; i++)
  {
    for(int j = 0; j < W - 1 + i % 2; j++)
      cin >> mem[j][i];
  }

  d[0][0] = 1;
  queue<int> q;
  q.push(0); q.push(0);
  while(!q.empty())
  {
    int x = q.front(); q.pop();
    int y = q.front(); q.pop();
    if(x == W - 1 && y == H - 1)
    {
      cout << d[x][y] << endl;
      goto loop;
    }
    for(int i = 0; i < 4; i++)
    {
      int tx = x + dx[i];
      int ty = y + dy[i];
      if(tx >= 0 && tx < W && ty >= 0 && ty < H && !d[tx][ty])
      {
        if(dx[i] == 1 && !mem[x][ty * 2] ||
           dx[i] == -1 && !mem[tx][ty * 2] ||
           dy[i] == 1 && !mem[tx][y * 2 + 1] ||
           dy[i] == -1 && !mem[tx][ty * 2 + 1])
        {
          q.push(tx); q.push(ty);
          d[tx][ty] = d[x][y] + 1;
        }
      }
    }
  }
  cout << 0 << endl;
  goto loop;
}

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

#define UP 0x01
#define RIGHT 0x02
#define DOWN 0x04
#define LEFT 0x08

#define MAX 31

static const int dir[] = {UP,RIGHT,DOWN,LEFT};
static const int di[] = {-1,0,1,0};
static const int dj[] = {0,1,0,-1};
static const int infty = 1 << 29;

using namespace std;

inline bool isinside(int i, int j, int h, int w)
{
  return 0<=i&&i<h&&0<=j&&j<w;
}

struct Tile{
  int adj;  // bit link
  int cost;
  Tile():adj(0),cost(infty){}
};

int bfs(int sti, int stj, int h, int w, Tile M[][MAX]){
  queue< pair<int,int> > qp;
  bool vis[MAX][MAX] = {{false,},};

  qp.push( make_pair(sti,stj) );
  M[sti][stj].cost = 0;
  while(!qp.empty()){
    pair<int,int> now = qp.front();
    qp.pop();
    int ni = now.first, nj = now.second;
    //cout << M[ni][nj].adj << endl;
    for(int k=0;k<sizeof(di)/sizeof(*di);++k){
      int nxi = now.first + di[k];
      int nxj = now.second + dj[k];
      if( isinside( nxi, nxj, h, w ) ){
	if( (M[ni][nj].adj & dir[k]) &&
	    !vis[nxi][nxj] ){
	  M[nxi][nxj].cost = min( M[nxi][nxj].cost, M[ni][nj].cost + 1 );
	  vis[nxi][nxj]=true;
	  qp.push( make_pair( nxi, nxj ) );
	}
      }
    }
  }

  return M[h-1][w-1].cost;
}

int main()
{
  while(true){
    int w,h;
    cin >> w >> h;
    if( w == 0 && h == 0 ) break;
    Tile M[MAX][MAX];
    for(int i = 0; i < 2*h - 1; ++i){
      for(int j = 0; j < w-(i%2==0?1:0); ++j){
	int d;
	cin >> d;
	if( d==0 ){
	  if( i % 2 == 0 ){
	    M[i/2][j].adj |= RIGHT;
	    M[i/2][j+1].adj |= LEFT;
	  }else{
	    M[(i-1)/2][j].adj |= DOWN;
	    M[(i-1)/2+1][j].adj |= UP;
	  }
	}
      }
    }
    /*
    for(int i = 0; i < h; ++i){
      for(int j = 0; j < w; ++j){
	cout << M[i][j].adj << ' ';
      }
      cout << endl;
    }
    cout << endl;
    */
    int ans = bfs( 0,0,h,w,M )+1;
    if( ans >= infty )
      cout << "0" << endl;
    else cout << ans << endl;
  }
  return 0;
}