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 <vector>
#include <utility>
#include <queue>

using namespace std;

typedef pair<int, int> P;


int w, h;
vector<vector<int>> wall_v;
vector<vector<int>> wall_h;
vector<vector<bool>> unreached;
vector<vector<unsigned int>> min_length;
queue<P> Q;

bool in(int x, int y);
void go();

int main()
{
    while(1){
        cin >> w >> h;
        if(w == 0) break;
        
        wall_v.resize(w);
        for(int i = 0; i < w; i++){
            wall_v[i].resize(h-1);
        }
        wall_h.resize(w-1);
        for(int i = 0; i < w-1; i++){
            wall_h[i].resize(h);
        }
        unreached.resize(w);
        for(int i = 0; i < w; i++){
            unreached[i].resize(h);
        }
        min_length.resize(w);
        for(int i = 0; i < w; i++){
            min_length[i].resize(h);
        }

        for(int i = 0; i < h-1; i++){
            for(int j = 0; j < w-1; j++){
                cin >> wall_h[j][i];
            }
            for(int j = 0; j < w; j++){
                cin >> wall_v[j][i];
            }
        }
        for(int j = 0; j < w-1; j++){
            cin >> wall_h[j][h-1];
        }    
        
        for(int i = 0; i < w; i++){
            for(int j = 0; j < h; j++){
                unreached[i][j] = true;
            }
        }
        for(int i = 0; i < w; i++){
            for(int j = 0; j < h; j++){
                min_length[i][j] = -1;
            }
        }
        
        min_length[0][0] = 1;
        Q.push(make_pair(0,0));
        go();

        if(unreached[w-1][h-1]){
            cout << "0" << endl;
        } else {
           cout << min_length[w-1][h-1] << endl;
        }
    }
    return 0;
}

bool in(int x, int y)
{
    return (x>=0 && x<w && y>=0 && y<h);

}

void go()
{
    
    int dx, dy;
    int x, y;
    // cout << "x, y: " << x << ", " << y << endl;
    // cout << "length: " << min_length[x][y] << endl;

    while(!Q.empty()){
        P pos = Q.front();
        Q.pop();
        x = pos.first;
        y = pos.second;
        unreached[x][y] = false;

        if(x == w-1 && y == h-1){
            break;
        }

        dx = 0;
        dy = 1;
        if(in(x+dx, y+dy)){
            if(unreached[x+dx][y+dy] && wall_v[x][y] == 0){
                min_length[x+dx][y+dy] = min_length[x][y] + 1;
                Q.push(make_pair(x+dx, y+dy));
            }
        }

        dx = 1;
        dy = 0;
        if(in(x+dx, y+dy)){
            if(unreached[x+dx][y+dy] && wall_h[x][y] == 0){
                min_length[x+dx][y+dy] = min_length[x][y] + 1;
                Q.push(make_pair(x+dx, y+dy));
            }
        }

        dx = 0;
        dy = -1;
        if(in(x+dx, y+dy)){
            if(unreached[x+dx][y+dy] && wall_v[x][y-1] == 0){
                min_length[x+dx][y+dy] = min_length[x][y] + 1;
                Q.push(make_pair(x+dx, y+dy));
            }
        }


        dx = -1;
        dy = 0;
        if(in(x+dx, y+dy)){
            if(unreached[x+dx][y+dy] && wall_h[x-1][y] == 0){
                min_length[x+dx][y+dy] = min_length[x][y] + 1;
                Q.push(make_pair(x+dx, y+dy));
            }
        }
    }
}