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 <queue>
using namespace std;
#define MAX 100000
int main(){
	char field[31][31];
	int width,height,data[31][31],n;
	char x,y;
	typedef pair<int,int> P;
	P p;
	queue<P> que;
	while(cin>>width>>height){
		if(width==0 && height==0){break;}
		//初期化
		for(x=0;x<=width;x++){
			for(y=0;y<=height;y++){
				field[x][y]=0;
				data[x][y]=MAX;
			}
		}
		//枠組み
		for(x=0;x<width;x++){
			field[x][0]|=2;
			field[x][height]|=2;
		}
		for(y=0;y<height;y++){
			field[0][y]|=1;
			field[width][y]|=1;
		}
		//壁
		for(y=0;y<height;y++){
			for(x=1;x<width;x++){
				cin>>n;
				if(n==1){
					field[x][y]|=1;
				}
			}
			if(y<height-1){
				for(x=0;x<width;x++){
					cin>>n;
					if(n==1){
						field[x][y+1]|=2;
					}
				}
			}
		}
		//初期値
		que.push(P(0,0));
		data[0][0]=1;
		//queが空になるまで繰り返し
		while(que.size()>0){
			p=que.front();
			que.pop();
			if((field[p.first][p.second]&2)==0){
				if(data[p.first][p.second-1]==MAX){
					data[p.first][p.second-1]=data[p.first][p.second]+1;
					if(p.first==width-1 && p.second-1==height-1){break;}
					que.push(P(p.first,p.second-1));
				}
			}
			if((field[p.first+1][p.second]&1)==0){
				if(data[p.first+1][p.second]==MAX){
					data[p.first+1][p.second]=data[p.first][p.second]+1;
					if(p.first+1==width-1 && p.second==height-1){break;}
					que.push(P(p.first+1,p.second));
				}
			}
			if((field[p.first][p.second+1]&2)==0){
				if(data[p.first][p.second+1]==MAX){
					data[p.first][p.second+1]=data[p.first][p.second]+1;
					if(p.first==width-1 && p.second+1==height-1){break;}
					que.push(P(p.first,p.second+1));
				}
			}
			if((field[p.first][p.second]&1)==0){
				if(data[p.first-1][p.second]==MAX){
					data[p.first-1][p.second]=data[p.first][p.second]+1;
					if(p.first-1==width-1 && p.second==height-1){break;}
					que.push(P(p.first-1,p.second));
				}
			}
		}
		cout<<((data[width-1][height-1]==MAX)?0:data[width-1][height-1])<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
using ll = long long;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=1e9+7 ;


void solve(int h,int w){
    vector<vector<int>> v(h*w);
    rep(i,h){
        rep(j,w-1){
            int x;
            cin>>x;
            if(!x){
                v[i*w+j].push_back(i*w+j+1);
                v[i*w+j+1].push_back(i*w+j);
            }
        }
        if(i==h-1)break;
        rep(j,w){
            int x;
            cin>>x;
            if(!x){
                v[i*w+j].push_back((i+1)*w+j);
                v[(i+1)*w+j].push_back(i*w+j);
            }
        }
    }
    vector<int> dist(h*w,inf);
    dist[0]=1;
    queue<int> que;
    que.push(0);
    while(que.size()){
        int cur=que.front();
        que.pop();
        for(auto to :v[cur]){
            if(dist[to]>dist[cur]+1){
                dist[to]=dist[cur]+1;
                que.push(to);
            }
        }
    }
    if(dist[h*w-1]==inf)cout<<-1<<endl;
    else cout<<dist[h*w-1]<<endl;
}
int main(){
    int w,h;
    while(cin>>w>>h,w!=0)solve(h,w);
    return 0;
}