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 <cstdio>
#include <cstdlib>
using namespace std;

int **wall_h;
int **wall_v;
int **tile;
int w,h;

void dfs(int x,int y,int depth);

int main(){
	while(1){
		cin >> w >> h ;
		if(!w){
			break;
		}
		wall_h = new int*[w];
		wall_v = new int*[w];
		for (int i=0;i<w;i++){
			wall_h[i] = new int[h];
			wall_v[i] = new int[h];
		}
		
		for (int i=0; i<h-1; i++) {
			for (int j=0; j<w-1; j++) {
				cin >> wall_v[j][i];
			}
			wall_v[w-1][i] = 1;
			for (int j=0; j<w; j++) {
				cin >> wall_h[j][i];
			}
		}
		for (int j=0; j<w-1; j++) {
			cin >> wall_v[j][h-1];
		}
		wall_v[w-1][h-1] = 1;
		for (int j=0; j<w; j++) {
			wall_h[j][h-1] = 0;
		}
		
		tile = new int*[w];
		for (int i=0; i<w; i++) {
			tile[i] = new int[h];
			for (int j=0; j<h; j++) {
				tile[i][j] = 0;
			}
		}
		dfs(0,0,1);

		cout << tile[w-1][h-1] << endl;
		
		
		for (int i=0; i<w; i++) {
			delete [] tile[i];
			delete [] wall_v[i];
			delete [] wall_h[i];
		}
		delete [] tile;
		delete [] wall_v;
		delete [] wall_h;
	}
	return 0;
}

void dfs(int x,int y,int depth){
	if (tile[x][y] == 0 || tile[x][y] > depth) {
		tile[x][y] = depth;
		if (x != 0 && wall_v[x-1][y] == 0) {
			dfs(x-1,y,depth+1);
		}
		if (x!=w-1 && wall_v[x][y] == 0) {
			dfs(x+1,y,depth+1);
		}
		if (y!=0 && wall_h[x][y-1] ==0) {
			dfs(x,y-1,depth+1);
		}
		if (y!=h-1 && wall_h[x][y] ==0) {
			dfs(x,y+1,depth+1);
		}
	}
	return;
	
}

C++: #include<iostream>
#include<vector>
#include<map>
#include<set>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<string>
#include<queue>
#include<complex>
#include<numeric>
#include<bitset>
#define INF 1001001001
#define EPS 0.000000001
#define x first
#define y second

using namespace std;
typedef vector<int> vint;
typedef vector<vint> vvint;
typedef pair<int,int> pint;

int dx[4] = {-1,0,1,0};
int dy[4] = {0,-1,0,1};
//int dx[8] = {0,1,1,1,0,-1,-1,-1};
//int dy[8] = {1,1,0,-1,-1,-1,0,1};

int nextInt(){
	int x;
	scanf("%d",&x);
	return x;
}

int main(){
	while(1){
		int w = nextInt();
		int h = nextInt();
		if(w==0 && h==0) break;
		int i,j;
		
		int maze[40][40][4];
		memset(maze, 0, sizeof(maze));
		
		for(j=0; j<w-1; j++){
			int w = nextInt();
			if(w==0){
				maze[0][j][3]=1;
				maze[0][j+1][1]=1;
			}
		}
		for(i=0; i<h-1; i++){
			for(j=0; j<w; j++){
				int w = nextInt();
				if(w==0){
					maze[i][j][2]=1;
					maze[i+1][j][0]=1;
				}
			}
			for(j=0; j<w-1; j++){
				int w = nextInt();
				if(w==0){
					maze[i+1][j][3]=1;
					maze[i+1][j+1][1]=1;
				}
			}
		}
		
		int memo[40][40];
		for(i=0; i<40; i++) for(j=0; j<40; j++) memo[i][j]=-1;
		memo[0][0]=1;
		
		queue<pint> q;
		q.push(pint(0, 0));
		int f=0;
		while(!q.empty() && f==0){
			pint p = q.front(); q.pop();
			for(i=0; i<4; i++){
				if(maze[p.x][p.y][i]==1){
					if(memo[p.x+dx[i]][p.y+dy[i]]==-1){
						if(p.x+dx[i]==h-1 && p.y+dy[i]==w-1){
							f=memo[p.x][p.y]+1;
						}
						memo[p.x+dx[i]][p.y+dy[i]]=memo[p.x][p.y]+1;
						q.push(pint(p.x+dx[i], p.y+dy[i]));
					}
				}
			}
		}
		
		printf("%d\n", f);
		
				
	}
	return 0;
}