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<string>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
#include<stack>
#include<queue>
#include<cmath>
#include<numeric>
using namespace std;

typedef pair<int,pair<int,int> > pp;
#define F first
#define S second.first
#define T second.second
#define MK make_pair


int main(){
    while(1){
    
    
    
    
    
    
    
    const int M=-1000000000;
    bool a[40][40][40][40]={};
    int w,h;
    cin>>w>>h;
        if(w==0 && h==0){break;}
    for(int i=0;i<h;i++){
        for(int t=0;t<w-1;t++){
            int c;
            cin>>c;
            if(c==0){
                a[i][t][i][t+1]=true;
                a[i][t+1][i][t]=true;
            }
        }
        if(i!=h-1){
            for(int t=0;t<w;t++){
                int c;
                cin>>c;
                if(c==0){
                    a[i][t][i+1][t]=1;
                    a[i+1][t][i][t]=1;
                }
            }
        }
    }
    
    priority_queue<pp> q;
    pp t=MK(-1,MK(0,0));
    q.push(t);
    bool done[40][40]={};
    int dis[40][40];
    fill(&dis[0][0],&dis[39][40],M);
    dis[0][0]=-1;
    while(!q.empty()){
        pp n=q.top();
        q.pop();
        if(done[n.S][n.T]){continue;}
        done[n.S][n.T]=true;
        
        if(n.S!=h-1 && a[n.S][n.T][n.S+1][n.T] && dis[n.S+1][n.T]<dis[n.S][n.T]-1){
            dis[n.S+1][n.T]=dis[n.S][n.T]-1;
            pp k=MK(dis[n.S+1][n.T],MK(n.S+1,n.T));
            q.push(k);
        }
        if(n.S!=0 && a[n.S][n.T][n.S-1][n.T] && dis[n.S-1][n.T]<dis[n.S][n.T]-1){
            dis[n.S-1][n.T]=dis[n.S][n.T]-1;
            pp k=MK(dis[n.S-1][n.T],MK(n.S-1,n.T));
            q.push(k);
        }
        if(n.T!=w-1 && a[n.S][n.T][n.S][n.T+1] && dis[n.S][n.T+1]<dis[n.S][n.T]-1){
            dis[n.S][n.T+1]=dis[n.S][n.T]-1;
            pp k=MK(dis[n.S][n.T+1],MK(n.S,n.T+1));
            q.push(k);
        }
        if(n.T!=0 && a[n.S][n.T][n.S][n.T-1] && dis[n.S][n.T-1]<dis[n.S][n.T]-1){
            dis[n.S][n.T-1]=dis[n.S][n.T]-1;
            pp k=MK(dis[n.S][n.T+1],MK(n.S,n.T-1));
            q.push(k);
        }
    }
    /*
    cout<<endl;
    for(int i=0;i<h;i++){
        for(int t=0;t<w;t++){
            cout<<-1*dis[i][t]<<" ";
        }
        cout<<endl;
    }
    */
    cout<<(dis[h-1][w-1]==M? 0:-1*dis[h-1][w-1])<<endl;
        
        
        
        
        
        
        
        
    }
    
    
    return 0;
}

C++: #include <iostream>
#include <queue>
#define MAX_W 30
#define MAX_H 30
using namespace std;

typedef pair<int, int> P;

int a[MAX_H * 2][MAX_W];
int d[MAX_H][MAX_W];
bool visited[MAX_H][MAX_W];

void bfs(int w, int h) {
  P t;
  t.first = t.second = 0;
  d[0][0] = 1;
  visited[0][0] = true;
  queue<P> que;
  que.push(t);

  while (que.empty() == false) {
    t = que.front();
    que.pop();
    P s;
    s.first = t.first - 1;
    s.second = t.second;
    if (s.first >= 0 && a[s.first * 2 + 1][s.second] == 0
	&& visited[s.first][s.second] == false) {
      d[s.first][s.second] = d[t.first][t.second] + 1;
      visited[s.first][s.second] = true;
      que.push(s);
    }
    s.first = t.first + 1;
    s.second = t.second;
    if (s.first < h && a[t.first * 2 + 1][s.second] == 0
	&& visited[s.first][s.second] == false) {
      d[s.first][s.second] = d[t.first][t.second] + 1;
      visited[s.first][s.second] = true;
      que.push(s);
    }
    s.first = t.first;
    s.second = t.second - 1;
    if (s.second >= 0 && a[s.first * 2][t.second] == 0
	&& visited[s.first][s.second] == false) {
      d[s.first][s.second] = d[t.first][t.second] + 1;
      visited[s.first][s.second] = true;
      que.push(s);
    }
    s.first = t.first;
    s.second = t.second + 1;
    if (s.second < w && a[s.first * 2][s.second] == 0
	&& visited[s.first][s.second] == false) {
      d[s.first][s.second] = d[t.first][t.second] + 1;
      visited[s.first][s.second] = true;
      que.push(s);
    }
  }
}

void init() {
  for (int i = 0; i < MAX_H * 2 + 1; i++) {
    for (int j = 0; j < MAX_W; j++) {
      a[i][j] = 0;
    }
  }
  for (int i = 0; i < MAX_H; i++) {
    for (int j = 0; j < MAX_W; j++) {
      d[i][j] = 0;
      visited[i][j] = false;
    }
  }
}

int main() {
  while (true) {
    int w, h;
    cin >> w >> h;
    if (w == 0 && h == 0) return 0;

    init();
    int flag = 0;
    for (int i = 0; i < h * 2 - 1; i++) {
      if (flag == 0) {
	for (int j = 1; j < w; j++) {
	  cin >> a[i][j];
	}
	flag = 1;
      } else {
	for (int j = 0; j < w; j++) {
	  cin >> a[i][j];
	}
	flag = 0;
      }
    }

    bfs(w, h);
    cout << d[h - 1][w - 1] << endl;
  }
}