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++)

using namespace std;

const int inf = 1e8;

int main(){
  int H, W;
  while(cin >> W >> H, H != 0){
    int sz = H* W;
    vector<vector<int>> g(sz, vector<int>(sz, inf));
    rep(i, sz) g[i][i] = 0;

    rep(y, H) {

      rep(x, W - 1){
        int n; cin >> n;
        int l = (n == 1) ? inf : 1;
          g[y * W + x][y * W + (x + 1)] = g[y * W + (x + 1)][y * W + x] = l; 
      }
      if(y == H - 1) break;
      rep(x, W){
        int n; cin >> n;
        int l = (n == 1) ? inf : 1;
          g[y * W + x][(y + 1) * W + x] = g[(y + 1) * W + x][y * W + x] = l;
        
      }
    }
      
   
    vector<vector<int>> a(sz);
    rep(i, sz){
       rep(j, sz){
           if(g[i][j] == 1) a[i].push_back(j);
       }
    }
    
    deque<tuple<int, int>> q;
    vector<int> vis(sz, inf);
    vis[0] = 0;
    q.emplace_back(0, 0);
    while(q.size() > 0){
      int h, s; tie(h, s) = q.back(); q.pop_back();
      for(auto&& k : a[h]){
          if(vis[k] == inf){
              vis[k] = s + 1;
              q.emplace_back(k, s + 1);
          }
      }
    }
    int res = vis[sz - 1] + 1;
    cout << ((res >= inf) ? 0 : res) << endl;
  }
}

C++: #include<iostream>
#include<vector>
#include<queue>
using namespace std;
	int w,h;
	typedef struct{
		int x;
		int y;
		int step;
	}P;
int main(){
	while(cin>>w>>h, w|h){
	bool wall;
	vector<vector<bool> > wmap(h),hmap(h-1);
	for(int j=0;j<h;j++){
		for(int i=0;i<w-1;i++){
			cin>>wall;
			wmap[j].push_back(wall);
		}
	if(j==h-1)break;
		for(int i=0;i<w;i++){
			cin>>wall;
			hmap[j].push_back(wall);
		}
	}
	queue<P> q;
	P p1;
	p1.x=0;
	p1.y=0;
	p1.step=1;
	q.push(p1);
	P p;
	int step=0;
	while(!q.empty()){
	p=q.front();q.pop();
	//left
	if(p.x-1>=0&&!wmap[p.y][p.x-1]){
	wmap[p.y][p.x-1]=1;
	p1.x=p.x-1;
	p1.y=p.y;
	p1.step=p.step+1;
	q.push(p1);
	}
	//up
	if(p.y-1>=0&&!hmap[p.y-1][p.x]){
	hmap[p.y-1][p.x]=1;
	p1.x=p.x;
	p1.y=p.y-1;
	p1.step=p.step+1;
	q.push(p1);
	}
	//right
	if(p.x+1<w&&!wmap[p.y][p.x]){
	wmap[p.y][p.x]=1;
	p1.x=p.x+1;
	p1.y=p.y;
	p1.step=p.step+1;
	q.push(p1);
	}
	//down
	if(p.y+1<h&&!hmap[p.y][p.x]){
	hmap[p.y][p.x]=1;
	p1.x=p.x;
	p1.y=p.y+1;
	p1.step=p.step+1;
	q.push(p1);
	}
	if(p.x==w-1&&p.y==h-1){
		step=p.step;
		break;
	}
	}

	cout<<step<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define MOD 1000000007
#define mkp make_pair
typedef long long ll;
using namespace std;

int H,W;
bool wall[33][33][4];

int dist[33][33];
int dx[]={0,1,-1,0};
int dy[]={1,0,0,-1};

int bfs(){
  for(int i=0;i<H;i++) for(int j=0;j<W;j++) dist[i][j]=MOD;
  dist[0][0]=0;
  queue<pair<int,int>> Q;
  Q.push(mkp(0,0));
  while(!Q.empty()){
    int x,y;
    tie(x,y)=Q.front();
    Q.pop();

    if(x==H-1&&y==W-1) return dist[H-1][W-1];

    for(int i=0;i<4;i++){
      int nx=x+dx[i];
      int ny=y+dy[i];
      if(nx<0||ny<0||nx>=H||ny>=W) continue;
      if(dist[nx][ny]<MOD) continue;
      if(wall[x][y][i]) continue;
      dist[nx][ny]=dist[x][y]+1;
      Q.push(mkp(nx,ny));
    }
    
  }
  return -1;
}

void solve(){
  for(int i=0;i<H;i++){
    for(int j=0;j<W;j++){
      for(int k=0;k<4;k++){
        wall[i][j][k]=false;
      }
    }
  }
  for(int i=0;i<H;i++){
    for(int j=0;j<W-1;j++){
      int x;
      cin>>x;
      if(x==1){
        wall[i][j][0]=true;
        wall[i][j+1][3]=true;
      }
    }
    if(i==H-1) break;

    for(int j=0;j<W;j++){
      int x;
      cin>>x;
      if(x==1){
        wall[i][j][1]=true;
        wall[i+1][j][2]=true;
      }
    }
  }
  int ans=bfs();
  if(ans==-1) cout<<0<<endl;
  else cout<<ans+1<<endl;
}

int main(){
  while(1){
    cin>>W>>H;
    if(W==0) break;
    solve();
  }

  return 0;
}