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;

typedef pair<int, int> P;
const int INF = numeric_limits<int>::max() / 2;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

    int w,h;
    while(cin>>w>>h,w||h){
        vector< vector<int> > dis(1000,vector<int>(1000,0));
        for(int i=0;i<1000;i++){
            dis[i][i]=0;
        }
        for(int i=0;i<2*h-1;i++){
            if(i%2==0){// ?¨??£?
                for(int j=0;j<w-1;j++){
                    int k;cin>>k;
                    int y=j,x=i/2;
                    if(k) continue;
                    dis[x*w+y][x*w+y+1]=dis[x*w+y+1][x*w+y]=1;
                }
            }
            else{
                for(int j=0;j<w;j++){
                    int k;cin>>k;
                    int y=j,x=i/2;
                    if(k) continue;
                    dis[x*w+y][x*w+y+w]=dis[x*w+y+w][x*w+y]=1;
                }
            }
        }
        int pt=w*h;
        /* TLE?§£
        for(int k=0;k<p;k++){
            for(int i=0;i<p;i++){
                for(int j=0;j<p;j++){
                    dis[i][j]=min(dis[i][k]+dis[k][j],dis[i][j]);
                }
            }
        }*/
        vector<int> res(1000,INF);
        res[0]=1;
        queue<int> q;
        q.push(0);
        while(!q.empty()){
            int p =q.front();q.pop();
            if(p+1<pt && (p+1)%w!=0 && res[p+1]==INF && dis[p][p+1]){
                q.push(p+1);res[p+1]=res[p]+1;
            } 
            if(p-1>=0 && p%w!=0 && res[p-1]==INF && dis[p][p-1]){
                q.push(p-1);res[p-1]=res[p]+1;
            }
            if(p+w<pt && res[p+w]==INF && dis[p][p+w]){
                q.push(p+w);res[p+w]=res[p]+1;
            }
            if(p-w>=0 && res[p-w]==INF && dis[p][p-w]){
                q.push(p-w);res[p-w]=res[p]+1;
            }
        }
        if(res[pt-1]==INF) cout<<0<<endl;
        else cout<<res[pt-1]<<endl;
    }
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>

using namespace std;

typedef long long ll;
#define REP(i,b,n) for(int i=b;i<n;i++)
#define rep(i,n) REP(i,0,n)
int w,h;
char maze[40][40];
typedef pair<pair<int,int> , int > State;
int d[2][4]={{1,0,-1,0},{0,1,0,-1}};
void solve(){
  queue<State> q;
  pair<int,int> goal(2*w-2,2*h-2);
  q.push(State(make_pair<int,int>(0,0),1));
  while(!q.empty()){
    State cur = q.front();q.pop();
    for(int i=0;i<4;i++){
      int nx=cur.first.first+d[0][i];
      int ny=cur.first.second+d[1][i];
      if(goal==cur.first){
	cout<<cur.second<<endl;
	return ;
      }
      if(nx<0||ny<0||nx>goal.first||ny>goal.second||maze[ny][nx]=='1')continue;
      nx+=d[0][i];
      ny+=d[1][i];
      if(nx<0||ny<0||nx>goal.first||ny>goal.second||maze[ny][nx]=='1')continue;
      maze[ny][nx]='1';
      q.push(State(make_pair<int,int>(nx,ny),cur.second+1));
    }
  }
  cout<<0<<endl;
  return;
}
void show(){
  rep(i,h*2-1){
    rep(j,w*2-1){
      cout<<maze[i][j];
    }
    cout<<endl;
  }
  cout<<endl;
}
int main(){
  while(cin >> w >> h && (w||h)){
    for(int i=0;i<40;i++)for(int j=0;j<40;j++)maze[i][j]='0';
    for(int i=0;i<h*2-1;i++){
      if(i%2){
	for(int j=0;j<w;j++)cin>>maze[i][j*2];
      }
      else{
	for(int j=0;j<w-1;j++)cin>>maze[i][j*2+1];
      }
    }
    solve();
  }
  return 0;
}