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>

#define rep(i,n) for(int i = 0; i < (n); i++)
#define rrep(i,n) for(int i = (n)-1; i >= 0; i--)
#define rep1(i,n) for(int i = 1; i <= (n); i++)
#define rrep1(i,n) for(int i = (n); i > 0; i--)

#define ll long long
#define pi pair<int, int>
#define pll pair<ll, ll>

#define MOD 1000000007
#define INF 1000000000000000LL

using namespace std;

int w,h;
vector<pi> g[31][31];
int d[31][31];

void connect(pi l, pi r){
  g[l.first][l.second].push_back(r);
  g[r.first][r.second].push_back(l);
}

void clear_all(){
  rep(i, 31)rep(j, 31){
    g[i][j].clear();
    d[i][j]=0;
  }
}

int main(){
  while(true){
    cin>>w>>h;
    if(w==0)break;

    rep(y, 2*h-1){
      if(y%2==0){
        rep(x, w-1){
          int wall;cin>>wall;
          if(!wall){
            connect({y/2, x}, {y/2, x+1});
          }
        }
      }else{
        rep(x, w){
          int wall;cin>>wall;
          if(!wall){
            connect({y/2, x}, {y/2+1, x});
          }
        }
      }
    }

    queue< pair<pi, int> > q;
    q.push( {{0,0},1} );
    while( !q.empty() ){
      auto cp = q.front();q.pop();
      auto c = cp.first;
      int y = c.first, x = c.second;
      if(d[y][x]>0)continue;

      int cost = cp.second;
      d[y][x] = cost;
      for(auto p: g[y][x]){
        q.push({p, cost+1});
      }
    }
    cout<<d[h-1][w-1]<<endl;

    clear_all();
  }

  return 0;
}

C++: #include<cstdio>
#include<map>
#include<queue>
using namespace std;
int main()
{
	int w,h,i,j,t,c[]={1,0,-1,0,1},a[30][30],d,V=999,x,y;
	while(scanf("%d%d",&w,&h),w)
	{
		int m[30][30][4]={0};
		for(i=0;i<2*h-1;++i)
		{
			if(i&1)for(j=0;j<w;++j)scanf("%d",&t),m[i/2][j][3]=m[i/2+1][j][1]=!t;
			else for(j=0;j<w-1;++j)scanf("%d",&t),m[i/2][j][0]=m[i/2][j+1][2]=!t;
		}
		for(i=0;i<h;++i)for(j=0;j<w;++j)a[i][j]=V;
		typedef pair<int,int>P;
		queue<P>q;
		P p;
		q.push(P(0,0));
		q.push(P(-1,-1));
		d=1;
		while(q.size()>1)
		{
			p=q.front();q.pop();
			x=p.first,y=p.second;
			if(x<0){++d,q.push(p);continue;}
			if(a[y][x]<=d)continue;
			a[y][x]=d;
			for(i=0;i<4;++i)if(m[y][x][i])q.push(P(x+c[i],y+c[i+1]));
		}
		printf("%d\n",a[h-1][w-1]-V?a[h-1][w-1]:0);
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
#include <vector>
using namespace std;
int w,h;
char map[200][200];
class Node{
public:
	int x,y;
	int c;
	Node(int _x,int _y,int _c):x(_x),y(_y),c(_c){

	}
};
void show(){
	for(int i=0;i<h*2-1;i++){
		for(int j=0;j<w*2-1;j++)cout<<map[i][j];
		cout<<endl;
	}
	cout<<endl;
}
bool visited[200][200];
int dx[]={1,0,-1,0};
int dy[]={0,-1,0,1};
int bfs(){
	for(int i=0;i<100;i++)fill(visited[i],visited[i]+100,false);
	queue<Node> q;
	q.push(Node(0,0,1));
	visited[0][0]=true;
	int gw=2*w-2;
	int gh=2*h-2;
	while(!q.empty()){
		Node cur=q.front();q.pop();
//		map[cur.y][cur.x]='1';
		show();
		if(cur.x==gw&&cur.y==gh)return cur.c;
		for(int i=0;i<4;i++){
			int nx=cur.x+dx[i];
			int ny=cur.y+dy[i];
			if(nx<0||ny<0||nx>gw||ny>gh||map[ny][nx]=='1')continue;
			nx=nx+dx[i];
			ny=ny+dy[i];
			if(nx<0||ny<0||nx>gw||ny>gh||map[ny][nx]=='1')continue;
			map[ny][nx]='1';
			if(visited[ny][nx])continue;
			visited[ny][nx]=true;
			q.push(Node(nx,ny,cur.c+1));
		}
	}
	return 0;
}
void solve(){
	cout<<bfs()<<endl;
}
int main(){
	while(cin>>w>>h&&(w||h)){
		for(int i=0;i<100;i++)for(int j=0;j<100;j++)map[i][j]='0';
		int hline=h*2-1;
		for(int i=0;i<hline;i++){
			if(i%2){
				for(int j=0;j<w;j++)cin>>map[i][2*j];
			}
			else {
				for(int j=0;j<w-1;j++)cin>>map[i][1+2*j];

			}
		}
//		show();
		solve();
	}
	return 0;
}