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;

struct STATE{ int x, y, d; };

bool grid[32][32][32][32];
int d[32][32];

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};

int main()
{	
	int m, n;
	while (scanf("%d %d", &m, &n), n){
		memset(grid, false, sizeof(grid));
		
		for (int i = 1; i <= n; i++){
			for (int j = 1; j <= m - 1; j++){
				int a;
				scanf("%d", &a);
				if (!a){
					grid[i][j][i][j + 1] = 
					grid[i][j + 1][i][j] = true;
				}
			}
			if (i == n) continue;
			for (int j = 1; j <= m; j++){
				int a;
				scanf("%d", &a);
				if (!a){
					grid[i][j][i + 1][j] = 
					grid[i + 1][j][i][j] = true;
				}
			}
		}
		
		memset(d, -1, sizeof(d));
		queue<STATE> que;
		for (que.push((STATE){1, 1, 1}); que.size(); que.pop()){
			STATE st = que.front();
			if (d[st.x][st.y] != -1) continue;
			d[st.x][st.y] = st.d;
			//printf("%d %d\n", st.x, st.y);
			
			for (int i = 0; i < 4; i++){
				if (!grid[st.x][st.y][st.x + dx[i]][st.y + dy[i]]) continue;
				if (d[st.x + dx[i]][st.y + dy[i]] != -1) continue;
				que.push((STATE){st.x + dx[i], st.y + dy[i], st.d + 1});
			}
		}
		
		printf("%d\n", d[n][m]);
	}
	
	return 0;
}

C++: //8:05~9:00
#include <iostream>
#include <string>
#include <map>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;

#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)

#define all(v) v.begin(),v.end()
#define INF 1<<30
#define mp 
#define pb push_back

#define fi first
#define se second

#define each(it,c) for(auto it=(c).begin();it!=(c).end();it++)

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
typedef vector<pair<int, int> > vp;

typedef long long ll;
  

int s[62][62];
int w,h;

int bfs(int x,int y){
	queue <pii> qpi;
	queue <int> qd;
	qpi.push(make_pair(x,y));
	qd.push(0);
	int d=0;
	int dx[4] = {1,0,-1,0};//???????????????
	int dy[4] = {0,1,0,-1};
	while(!qpi.empty()){
		d = qd.front();
		qd.pop();
		x = qpi.front().fi;
		y = qpi.front().se;
		qpi.pop();
		s[y][x]=1;
		//?????????????????¶???
		rep(i,4){
			if(s[y+dy[i]][x+dx[i]]==0) {
				qpi.push(make_pair(x+dx[i],y+dy[i]));
				qd.push(d+1);
			}
		}
		// cout << x << "x y" << y << endl;
		// rep(y,h){
	 //  		rep(x,w){
	 //  			cout << s[y][x];
	 //  		}
	 //  		cout << endl;
	 //  	}
  		// cout << endl;
		if(x==w-2&&y==h-2) return d/2+1;
	}
	return 0;
}
int main(){
  while(1){
  	
  	cin >> w >> h;
  	if(w==0&&h==0) break;
  	w=w*2+1;
  	h=h*2+1;
  	rep(y,h){
  		rep(x,w){
  			s[y][x]=0;
  		}
  	}
  	rep(y,h){
  		rep(x,w){
  			if(y==0||x==0||y==h-1||x==w-1) s[y][x]=1;
  			else if((x+y)%2==1)cin >> s[y][x];
  			else if(x%2==0&&y%2==0) s[y][x]=1;
  			else s[y][x]=0;
  		}
  	}
  	
  	cout<<bfs(1,1)<<endl;

  	// rep(y,h){
  	// 	rep(x,w){
  	// 		cout << s[y][x];
  	// 	}
  	// 	cout << endl;
  	// }
  }
  return 0;
}