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>
#define INF 2000000000
#define N 30
using namespace std;
void bfs();
int w,h,data[N][N][4];//0:left,1:up,2:right,3:down
int main(){
  int l,in;
  while(1){
    cin >> w >> h;
    if(w==0&&h==0) break;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
    for(int k=0;k<4;k++){
      data[i][j][k]=1;
    }
      }
    }
    for(int i=0,l=0;i<2*h-1;i++){
      if(i%2==0){
    for(int j=0;j<w-1;j++){
      cin >> in;
      if(in==0) data[l][j][2]=data[l][j+1][0]=0;
    }
      }else{
    for(int j=0;j<w;j++){
      cin >> in;
      if(in==0) data[l][j][3]=data[l+1][j][1]=0;
    }
    l++;
      }
    }
    bfs();
  }
  return 0;
}
void bfs(){
  int d[h][w];
  queue<pair<int,int> > Q;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      d[i][j]=INF;
    }
  }
  d[0][0]=1;
  Q.push(make_pair(0,0));
  while(!Q.empty()){
    pair<int,int> u=Q.front();
    Q.pop();
    if(data[u.first][u.second][0]==0){
      if(d[u.first][u.second-1]>d[u.first][u.second]+1){
    d[u.first][u.second-1]=d[u.first][u.second]+1;
    Q.push(make_pair(u.first,u.second-1));
      }
    }
    if(data[u.first][u.second][1]==0){
      if(d[u.first-1][u.second]>d[u.first][u.second]+1){
    d[u.first-1][u.second]=d[u.first][u.second]+1;
    Q.push(make_pair(u.first-1,u.second));
      }
    }
    if(data[u.first][u.second][2]==0){
      if(d[u.first][u.second+1]>d[u.first][u.second]+1){
    d[u.first][u.second+1]=d[u.first][u.second]+1;
    Q.push(make_pair(u.first,u.second+1));
      }
    }
    if(data[u.first][u.second][3]==0){
      if(d[u.first+1][u.second]>d[u.first][u.second]+1){
    d[u.first+1][u.second]=d[u.first][u.second]+1;
    Q.push(make_pair(u.first+1,u.second));
      }
    }
  }
  if(d[h-1][w-1]!=INF) cout << d[h-1][w-1] << endl;
  else cout << 0 << endl;
}

C++: #include<stdio.h>
#include<iostream>
#include<math.h>
#include<algorithm>
#include<string>
#include<utility>
#include<queue>
#define pi 3.14159
#define Inf (int)pow(2., 20.)

using namespace std;
typedef std::pair<int, int> mypair;
int w, h, a[59][59];
queue<mypair> qu;
void bfs(int y, int x);

int main(){
	while(1) {
		cin >> w >> h;
		if(w == 0 && h == 0) break;
		for(int i = 0; i < 2*h-1; i++) {
			for(int j = 0; j < 2*w-1; j++) {
				if(i % 2 == 0 && j % 2 == 0) a[i][j] = Inf;
				else if(i % 2 == 1 && j % 2 == 1) a[i][j] = Inf;
				else cin >> a[i][j];
			}
		}
		a[0][0] = 1;
		if(a[0][1] == 0) {
			qu.push(mypair(0, 2));
			a[0][2] = 2;
		}
		if(a[1][0] == 0) {
			qu.push(mypair(2, 0));
			a[2][0] = 2;
		}
		bfs(qu.front().first, qu.front().second);
		if(a[2*h-2][2*w-2] == Inf) cout << 0 <<endl;
		else cout << a[2*h-2][2*w-2] <<endl;
		
	}
	return 0;
}

void bfs(int y, int x) {
	qu.pop();
	
	if(y == 2*h-2 && x == 2*w-2) return;
	if(x + 1 < 2*w-1) {
		if(a[y][x+1] == 0 && a[y][x+2] > a[y][x] + 1) {
			qu.push(mypair(y, x+2));
			a[y][x+2] = a[y][x] + 1;
		}
	}
	if(y+1 < 2*h-1) { 
		if(a[y+1][x] == 0 && a[y+2][x] > a[y][x] + 1) {
			qu.push(mypair(y+2, x));
			a[y+2][x] = a[y][x] + 1;
		}
	}
	if(y - 1 >= 0) {
		if(a[y-1][x] == 0 && a[y-2][x] > a[y][x] + 1) {
			qu.push(mypair(y-2, x));
			a[y-2][x] = a[y][x] +1;
		}
	}
	if(x - 1 >= 0) {
		if(a[y][x-1] == 0 && a[y][x-2] > a[y][x] + 1) {
			qu.push(mypair(y, x-2));
			a[y][x-2] = a[y][x] + 1;
		}
	}
	if(qu.empty() == false) bfs(qu.front().first, qu.front().second);
	return;
}

C++: #include <iostream>
#include <memory>
#include <memory.h>
#include <queue>
#include <algorithm>
using namespace std;

typedef pair<int, int> P;
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
bool g[40][40][40][40];
int memo[40][40];

int main(){
  int w, h;
  int can;
  while(cin >> w >> h && (w || h)){
    
    memset(g, false, sizeof(g));
    for(int i = 1; i <= h * 2 - 1; i++){
      if(i % 2 == 1){
	for(int j = 1; j <= w - 1; j++){
	  cin >> can;
	  if(can == 0){
	    g[i/2+1][j][i/2+1][j+1] = true;
	    g[i/2+1][j+1][i/2+1][j] = true;
	  }
	}
	
      }else{
	for(int j = 1; j <= w; j++){
	  cin >> can;
	  if(can == 0){
	    g[i/2][j][i/2+1][j] = true;
	    g[i/2+1][j][i/2][j] = true;
	  }
	}
      }
    }
  
    memset(memo, -1, sizeof(memo));
    memo[1][1] = 1;
    queue<P> que;
    que.push(P(1, 1));
    while(!que.empty()){
      P p = que.front();
      que.pop();
      int y = p.first;
      int x = p.second;
      for(int i = 0; i < 4; i++){
	int y2 = y + dy[i];
	int x2 = x + dx[i];
	if(g[y][x][y2][x2] && memo[y2][x2] == -1){
	 
	  memo[y2][x2] = memo[y][x] + 1;
	  que.push(P(y2, x2));
	}
      }
    }
    int res = memo[h][w];
    if(res == -1) cout << 0 << endl;
    else cout << res << endl;
  }
  return 0;
}