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;
#define INF 1000000
//aizu 200???

//??±???????????¢?´¢??§??????????????????
//???????????????????????¢?´¢??§????????????
int h, w;
int di[4] = {0, 1, 0, -1};
int dj[4] = {1, 0, -1, 0};


int main(){
    while(1){
    cin >> w >> h;
    if(w == 0) break;
    vector<vector<bool> > canGo(2*h + 2, vector<bool> (2*w + 2, true));
    for(int i = 1; i <= 2*h - 1; i++){
        for(int j = 1; j <= 2*w - 1; j++){
            canGo[i][j] = false;
        }
    }

    //??\???
    for(int i = 1; i <= 2*h - 1; i++){
        if(i % 2 == 1){
            for(int j = 2; j <= 2*w - 1; j += 2){
                bool input; cin >> input;
                canGo[i][j] = input;
            }
        }else{
            for(int j = 1; j <= 2*w - 1; j+= 2){
                bool input; cin >> input;
                canGo[i][j] = input;
            }
        }
    }


    //??\??????????????¢?´¢
    queue<pair<int, pair<int, int> > > wait;
    wait.push(make_pair(0, make_pair(1, 1)));
    canGo[1][1] = true;

    //??\???????????????
    int ans = 0;   //ans???0??§?????????

    while(!wait.empty()){    //?????\???????????????????????§
        //?????\????????????????´????????????????
        int nowcost = wait.front().first;
        int nowi = wait.front().second.first;
        int nowj = wait.front().second.second;

        //cout << nowcost << " " << nowi << " " << nowj << endl;
        wait.pop();

        //??´??????????????????????????????????????????????????????
        if(nowi == 2*h - 1 && nowj == 2*w - 1){
            ans = nowcost;
            break;
        }

        //??????????????¢?´¢
        for(int k = 0; k < 4; k++){
            int nexti = nowi + 2*di[k];
            int nextj = nowj + 2*dj[k];

            //??????????????????????????????
            if(canGo[nowi + di[k]][nowj + dj[k]] == 0 && canGo[nexti][nextj] == 0){
                //????????????????????\???????????????
                //??????????´¢???????????¨?????????????£???§?????????
                wait.push(make_pair(nowcost + 1, make_pair(nexti, nextj)));
                canGo[nexti][nextj] = true;
            }
        }
    }

    if(ans == 0) cout << ans << endl;
    else cout << ans + 1 << endl;
    }
    return 0;

}