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));
    rep(i, sz) g[i][i] = 0;

    rep(y, H) {

      rep(x, W - 1){
        int n; cin >> n;
        if (n == 0){
          g[y * W + x].push_back(y * W + (x + 1));
          g[y * W + x + 1].push_back(y * W + x); 
        }
      }
      if(y == H - 1) break;
      rep(x, W){
        int n; cin >> n;
          if (n == 0){
          g[y * W + x].push_back((y + 1) * W + x);
          g[(y + 1) * W + x].push_back(y * W + x);
          }
      }
    }
    
    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 : g[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<string>
#include<algorithm>
#include<map>
#include<set>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<iomanip>
#define loop(i,a,b) for(long long i=a;i<b;i++)
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)	
#define show1d(v) rep(i,v.size())cout<<" "<<v[i];cout<<endl;
#define show2d(v) rep(i,v.size()){rep(j,v[i].size())cout<<" "<<v[i][j];cout<<endl;}cout<<endl;
using namespace std;
typedef long long ll;
typedef int Def;
typedef pair<Def,Def> pii;
typedef vector<Def> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<string> vs;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
Def inf = sizeof(Def) == sizeof(ll) ? 2e18 : 1e9+10;
int main(){
	int n,m;
	while(cin>>m>>n,n){
		vvi H(n-1,vi(m));
		vvi W(n,vi(m-1));
		rep(i,n-1){
			rep(j,m-1)cin>>W[i][j];
			rep(j,m)cin>>H[i][j];
		}
		rep(i,m-1)cin>>W[n-1][i];
		
		vvi dp(n,vi(m,inf));
		dp[0][0]=1;
		queue<pii>q;
		q.push({0,0});
		while(!q.empty()){
			pii t=q.front();
//			cout<<t.first<<" "<<t.second<<endl;
			q.pop();
			rep(i,4){
				int x=t.first+dx[i];
				int y=t.second+dy[i];
				if(x<0||y<0||x>=n||y>=m)continue;
				if(i==0&&W[t.first][t.second])continue;
				if(i==1&&H[t.first][t.second])continue;
				if(i==2&&W[t.first][t.second-1])continue;
				if(i==3&&H[t.first-1][t.second])continue;
				if(dp[x][y]>dp[t.first][t.second]+1){
					dp[x][y]=dp[t.first][t.second]+1;
					q.push({x,y});
				}
			}
		}
		if(dp[n-1][m-1]==inf)dp[n-1][m-1]=0;
		cout<<dp[n-1][m-1]<<endl;
	}
}

C++: #include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<climits>
using namespace std;

int w,h;
int check[40][40][40][40];
int ans;
vector<vector<int> > input;

int loop(int count){

  int flag=0;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(input[i][j]==count){
	if(i>0){
	  if(check[i][j][i-1][j]==0){
	    input[i-1][j]=min(input[i-1][j],count+1);
	    flag=1;
	  }
	}
	if(j>0){
	  if(check[i][j][i][j-1]==0){
	    input[i][j-1]=min(input[i][j-1],count+1);
	    flag=1;
	  }
	}

	if(i<h-1){
	  if(check[i][j][i+1][j]==0){
	    input[i+1][j]=min(input[i+1][j],count+1);
	    flag=1;
	  }
	}
	if(j<w-1){
	  if(check[i][j][i][j+1]==0){
	    input[i][j+1]=min(input[i][j+1],count+1);
	    flag=1;
	  }
	}
      }
    }
  }

  return flag;
}




int main(){

  while(cin >> w >> h,w||h){
    input.clear();
    input.resize(h);
    memset(check,0,sizeof(check));

    for(int i=0;i<h;i++){
      input[i].resize(w,INT_MAX);
	int tmp;
      for(int j=0;j<w-1;j++){
	cin >> tmp;
	check[i][j][i][j+1]=tmp;
	check[i][j+1][i][j]=tmp;
      }
      if(i!=h-1){
	for(int j=0;j<w;j++){
	  cin >>tmp;
	  check[i][j][i+1][j]=tmp;
	  check[i+1][j][i][j]=tmp;
	}
      }
    }

    /*    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++)
	cout << check[i][j][i+1][j] << " ";
      cout << endl;
      }*/

    //    return 0;
    input[0][0]=0;
    for(int i=0;;i++){
      //      cout << i << endl; 
      int tmp;
      if(loop(i)==0) break;
    }

    if(input[h-1][w-1]==INT_MAX)
      input[h-1][w-1]=(-1);
    cout << input[h-1][w-1]+1 << endl;
  }

  return 0;
}