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 int long long

bool isprime(int n){
    double rootn = sqrt(n);
    if (n < 2){
        return false;
    }
    else if (n == 2){
        return true;
    }
    else if (n % 2 == 0){
        return false;
    }
    else{
        for(int i = 3; i <= rootn; i += 2){
            if(n % i == 0){
                return false;
            }
        }
        return true;
    }
}

// 空のベクトルを二つ渡す。N (>=2) 以下の素数を primes に順番に入れる。
void prime_vectors(int N, vector<int>& primes, vector<bool>& is_prime){
    primes = {};
    is_prime = {};
    for(int i=0; i<=N; i++){
        is_prime.push_back(true);
    }

    primes.push_back(2);
    for(int j=4; j<=N; j+=2){
        is_prime[j] = false;
    }

    int i;
    for(i=3; i*i<=N; i+=2){
        if(!is_prime[i]) continue;
        primes.push_back(i);
        for(int j=2*i; j<=N; j+=i){
            is_prime[j] = false;
        }
    }

    for(; i<=N; i+=2){
        if(is_prime[i]){
            primes.push_back(i);
        }
    }
}

signed main(){
    // cout << fixed << setprecision(10) << flush;

    int w, h;
    cin >> w >> h;
    vector<int> ans = {};
    while(w != 0 && h != 0){
        int wall[h][w][4]; // 上が 0, 右が 1, ...        
        for(int i=0; i<h; i++){
            for(int j=0; j<w; j++){
                for(int e=0; e<4; e++){
                    wall[i][j][e] = 1;
                }
            }
        }

        for(int i=0; i<h; i++){
            for(int j=0; j<w-1; j++){
                int a;
                cin >> a;
                wall[i][j][1] = a;
                wall[i][j+1][3] = a;
            }
            if(i < h-1){
                // i=h-1 のときは下へは行かない
                for(int j=0; j<w; j++){
                    int a;
                    cin >> a;
                    wall[i][j][2] = a;
                    wall[i+1][j][0] = a;
                }
            }
        }

        queue<pair<int, int>> q;
        q.push(make_pair(0, 0));
        int min_d = 0;

        int dis[h][w];
        for(int i=0; i<h; i++){
            for(int j=0; j<w; j++){
                dis[i][j] = -1;
            }
        }
        dis[0][0] = 1;
        
        while(!q.empty()){
            int y = q.front().first;
            int x = q.front().second;
            q.pop();
            int dx[4] = {0, 1, 0, -1};
            int dy[4] = {-1, 0, 1, 0};

            for(int e=0; e<4; e++){
                if(wall[y][x][e] == 1){
                    // 壁なので通れない
                    // 領域外との通行もこれで防げるはず
                    continue;
                }
                int ny = y + dy[e];
                int nx = x + dx[e];
                if(dis[ny][nx] == -1){
                    q.push(make_pair(ny, nx));
                    dis[ny][nx] = dis[y][x] + 1;
                }
            }

            if(dis[h-1][w-1] != -1){
                // ゴールについた
                min_d = dis[h-1][w-1];
                break;
            }
        }
        ans.push_back(min_d); // ゴールにつかなかったときは min_d = 0 のまま
        cin >> w >> h;
    }

    for(int i=0; i<ans.size(); i++){
        cout << ans[i] << endl;
    }

    return 0;
}