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<stdio.h>
#include<iostream>
#include<math.h>
#include<algorithm>
#include<string>
#define pi 3.14159
#define Inf 9999
using namespace std;



int w, h, step, a[59][59];
void dfs(int y, int x);
int main(){
	while(1) {
		step = 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[1][0] == 0) dfs(2, 0);
		if(a[0][1] == 0) dfs(0, 2);
		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 dfs(int y, int x) {
	if(y < 0 || x < 0 || y >= 2*h-1 || x >= 2*w-1) return;
	if(step >= a[y][x]) return;
	else {
		step++;
		a[y][x] = step;
		if(y+1 < 2*h-1) { 
			if(a[y+1][x] == 0) dfs(y+2, x);
		}
		if(x + 1 < 2*w-1) {
			if(a[y][x+1] == 0) dfs(y, x+2);
		}
		if(y - 1 >= 0) {
			if(a[y-1][x] == 0) dfs(y-2, x);
		}
		if(x - 1 >= 0) {
			if(a[y][x-1] == 0) dfs(y, x-2);
		}
	}
	return;
}

C++: #include <iostream>
#include <queue>
#include <utility>
#include <algorithm>
#define REP(i,n) for(int i=0;i<(n);i++)
using namespace std;

typedef pair<int, int> pxy;

typedef struct{
  bool u, d, l, r;
}Wall;

int w, h;
Wall map[31][31];
int d[30][30];

bool bfs(int sx, int sy)
{
  queue<pxy> q;
  q.push(pxy(sx, sy));
  while(!q.empty()){
    int x, y;
    x = q.front().first;
    y = q.front().second;
    q.pop();
    if(x == h - 1 && y == w - 1) return true;
    if(!map[x][y].u){
      d[x-1][y] = min(d[x-1][y], d[x][y] + 1);
      q.push(pxy(x-1,y));
    }
    if(!map[x][y].d){
      d[x+1][y] = min(d[x+1][y], d[x][y] + 1);
      q.push(pxy(x+1,y));
    }
    if(!map[x][y].l){
      d[x][y-1] = min(d[x][y-1], d[x][y] + 1);
      q.push(pxy(x,y-1));
    }
    if(!map[x][y].r){
      d[x][y+1] = min(d[x][y+1], d[x][y] + 1);
      q.push(pxy(x,y+1));
    }
    map[x][y].u = map[x][y].d = map[x][y].l = map[x][y].r = true;
    if(x >= 1)
      map[x-1][y].d = true;
    if(y >= 1)
      map[x][y-1].r = true;
    map[x+1][y].u = map[x][y+1].l = true;
  }
  return false;
}

int main()
{
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    fill(&d[0][0], &d[31][0], 9999);
    d[0][0] = 1;
    REP(i,31){
      REP(j,31){
        map[i][j].u = map[i][j].d = map[i][j].l = map[i][j].r = false;
      }
    }
    REP(i,2*h-1){
      int x;
      if(i & 1){
        REP(j,w){
          cin >> x;
          if(x){
            map[i/2][j].d = map[i/2][j+1].u = true;
          }
        }
      }else{
        REP(j,w-1){
          cin >> x;
          if(x){
            map[i/2][j].r = map[i/2][j+1].l = true;
          }
        }
      }
    }
    REP(i,h)
      map[i][0].l = map[i][w-1].r = true;
    REP(i,w)
      map[0][i].u = map[h-1][i].d = true;
    if(bfs(0, 0))
      cout << d[h-1][w-1] << endl;
    else
      cout << "0" << endl;
  }
}

C++: #include<iostream>
#include<queue>
#include<vector>
#include<cstdio>
using namespace std;
#define max 70


class Node{
public:
	int cost;
	int x;
	int y;
	Node(int c,int _x,int _y){
		cost=c;
		x=_x;
		y=_y;
	}
};

typedef queue <Node> bq;
int map[max][max];
bool visited[max][max];
int dx[]={ 0, 1, 0,-1};
int dy[]={ 1, 0,-1, 0};
int w,h;

void init(){
	int i,j;
	for(i=0;i<max;i++){
		for(j=0;j<max;j++){
			map[i][j]=0;
			visited[i][j]=false;
		}
	}
}
void print(){
	int i,j;
	for(i=0;i<2*h-1;i++){
		if(i%2==0)cout<<"|";
		else cout<<" ";
		for(j=0;j<2*w;j++){
			if(i%2==0)printf("%s",map[i][j]?"|":" ");
			else printf("%s",map[i][j]?"_":" ");
		}
		if(i%2==0)cout<<"|";
		printf("\n");
	}
}
int bfs(){
	bq q;
	q.push(Node(1,0,0));


	while(!q.empty()){
		Node cur = q.front();q.pop();
		if(cur.x==2*(w-1) && cur.y==2*(h-1)){
			return cur.cost;
		}

		if(visited[cur.y][cur.x])continue;
		visited[cur.y][cur.x]=true;
		for(int i=0;i<4;i++){
			if(cur.y+dy[i]<0 || cur.y+dy[i]>2*(h-1) || cur.x+dx[i]<0 || cur.x+dx[i]>2*(w-1)
					|| map[cur.y+dy[i]][cur.x+dx[i]]==1)continue;
			q.push(Node(cur.cost+1, cur.x+2*dx[i], cur.y+2*dy[i]));
		}

	}
	return 0;
}
int main(){
	int i,j;
	while(cin>>w>>h&&(w||h)){
		init();
		for(i=0;i<2*h-1;i++){
			int k;
			if(i%2==0){
				for(j=0,k=1;j<w-1;j++){
					cin>>map[i][k];
					k+=2;
				}
			}
			else{
				for(j=0,k=0;j<w;j++){
					cin>>map[i][k];
					k+=2;
				}
			}
		}
		//print();
		cout<<bfs()<<endl;
		cout<<"-----------------------"<<endl;
	}
	return 0;
}