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;
using ll = long long;
using P = pair<int, int>;

#define rep(i, n) for (int i = 0; i < n; ++i)
#pragma region Debug
template <typename T>
void view(const std::vector<T> &v)
{
    for (const auto &e : v)
    {
        std::cout << e << " ";
    }
    std::cout << std::endl;
}
template <typename T>
void view(const std::vector<std::vector<T>> &vv)
{
    for (const auto &v : vv)
    {
        view(v);
    }
}
#pragma endregion

int main()
{
    int w, h;
    cin >> w >> h;
    do
    {
        vector<vector<vector<P>>> g(h, vector<vector<P>>(w, vector<P>()));
        int ls = 2 * h - 1;
        rep(i, ls)
        {
            int y = i / 2;
            if (i % 2 == 0)
            {
                rep(j, w - 1)
                {
                    int wall;
                    cin >> wall;
                    if (!wall)
                    {
                        g[y][j].emplace_back(P(y, j + 1));
                        g[y][j + 1].emplace_back(P(y, j));
                    }
                }
            }
            else
            {
                rep(j, w)
                {
                    int wall;
                    cin >> wall;
                    if (!wall)
                    {
                        g[y][j].emplace_back(P(y + 1, j));
                        g[y + 1][j].emplace_back(P(y, j));
                    }
                }
            }
        }

        queue<P> q;
        q.push(P(0, 0));
        vector<vector<int>> d(h, vector<int>(w, -1));
        d[0][0] = 1;
        while (q.size())
        {
            P n = q.front();
            q.pop();
            int ny = n.first,
                nx = n.second;
            if (n == P(h - 1, w - 1))
            {
                break;
            }

            for (P t : g[ny][nx])
            {
                int ty = t.first, tx = t.second;
                if (d[ty][tx] < 0)
                {
                    d[ty][tx] = d[ny][nx] + 1;
                    q.push(t);
                }
            }
        }

        cout << max(0, d[h - 1][w - 1]) << endl;

        cin >> w >> h;
    } while (w != 0 && h != 0);

    return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);i++)
using namespace std;
typedef pair <int,int> pii;
#define FST first
#define SEC second
#define WMAX 59
#define HMAX 59

int dd[5]={0,1,0,-1,0};
int w,h;

int dfs_aux(int map[WMAX][HMAX],int sx,int sy,int *min,int count){
  if(count<*min)
    rep(i,4){
      if(count>=*min)
	break;
      int nx=sx+dd[i],ny=sy+dd[i+1];
      if(nx<0 || w<=nx || ny<0 || h<=ny || map[nx][ny])
	continue;

      if(nx==w-1 && ny==h-1 && count<*min){
	*min=count;
	continue;
      }
    
      map[sx][sy]=1;
      dfs_aux(map,nx,ny,min,count+1);
      if(count<*min)
	break;
      map[sx][sy]=0;
    }
}

bool goal(int map[WMAX][HMAX]){
  stack <pii> s;
  s.push(pii(w-1,h-1));
  while(!s.empty()){
    int cx=s.top().FST, cy=s.top().SEC;
    s.pop();
    if(map[cx][cy]==0)
      map[cx][cy]=1;
    rep(r,4){
      int nx=cx+dd[r], ny=cy+dd[r+1];
      if(nx<0||w<=nx||ny<0||h<=ny||map[nx][ny])
	continue;
      s.push(pii(nx,ny));
    }
  }
  if(map[0][0])
    return true;
  return false;
}

int dfs(int map[WMAX][HMAX]){
  int copy[WMAX][HMAX];
  rep(i,h){
    rep(j,w){
      copy[j][i]=map[j][i];
    }
  }
  if(!goal(copy))
    return 0;

  int min=INT_MAX;
  dfs_aux(map,0,0,&min,0);
  return (min+3)/2;
}

void init_map(int map[WMAX][HMAX]){
  rep(i,2*h-1){
    rep(j,2*w-1){
      map[j][i]=0;
    }
  }
}

int main(){
  int map[WMAX][HMAX];
  for(;;){
    scanf("%d%d",&w,&h);
    if(!(w+h)) break;
    init_map(map);
    rep(i,h){
      rep(j,w-1){
	scanf("%d",&map[2*j+1][2*i]);
	if(map[2*j+1][2*i]){
	  if(0 <= 2*i-1)
	    map[2*j+1][2*i-1] = 1;
	  if(2*i+1 < 2*h-1)
	    map[2*j+1][2*i+1] = 1;
	}
      }
      if(i==h-1)break;
      rep(j,w){
	int m;
	scanf("%d",&map[2*j][2*i+1]);
	if(map[2*j][2*i+1]){
	  if(0 <= 2*j-1)
	    map[2*j-1][2*i+1] = 1;
	  if(2*j+1 < 2*w-1)
	    map[2*j+1][2*i+1] = 1;
	}
      }
    }
    w=2*w-1;
    h=2*h-1;
    printf("%d\n",dfs(map));
  }
}