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++: //http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1166&lang=jp

 #include<iostream>
 #include<vector>
 #include<queue>

 using namespace std;

 struct data{
     int x;
     int y;
 };

 int main(){

    while(1){
        int H,W;

        cin >> W >> H;
        cin.ignore();

        if(H+W == 0){
            break;
        }

        int distance[H][W];
        int dx[4] = {1,0,-1,0};
        int dy[4] = {0,1,0,-1};

        for(int i=0;i<H;i++){
            for(int j=0;j<W;j++){
                distance[i][j] = -1;
            }
        }

        int maze[2*H-1][W];
        for(int i=0;i<2*H-1;i++){
            if(i%2 == 0){
                for(int j=0;j<W-1;j++){
                    int a;
                    cin >> a;
                    maze[i][j] = a;
                }
                cin.ignore();
                maze[i][W-1] = -1;
            }else{
                for(int j=0;j<W;j++){
                    int a;
                    cin >> a;
                    maze[i][j] = a;
                }
                cin.ignore();
            }
        }

        data pos;
        pos.x = 0; pos.y = 0;
        queue<data> que;

        que.push(pos);
        distance[0][0] = 0;

        while(que.empty()==false){
            //cout << "-------------" << endl;

            data cur= que.front();
            que.pop();

            //cout << cur.x << "," << cur.y << endl;

            int nx = -1;
            int ny = -1;

            for(int i=0;i<4;i++){
                
                switch(i){
                    case 0:
                        //cout << "maze[" << 2*cur.y<<"]["<<cur.x<<"]="<<maze[2*cur.y][cur.x]<<endl;
                        if(cur.x != W-1 && maze[2*cur.y][cur.x] == 0){
                            nx = cur.x + dx[i];
                            ny = cur.y + dy[i];
                        }
                        break;
                    case 1:
                        //cout << "maze[" << 2*cur.y+1<<"]["<<cur.x<<"]="<<maze[2*cur.y+1][cur.x]<<endl;
                        if(cur.y != H-1 && maze[2*cur.y+1][cur.x] == 0){
                            nx = cur.x + dx[i];
                            ny = cur.y + dy[i];
                        }
                        break;
                    case 2:
                        //cout << "maze[" << 2*cur.y<<"]["<<cur.x-1<<"]="<<maze[2*cur.y][cur.x-1]<<endl;
                        if(cur.x != 0 && maze[2*cur.y][cur.x-1] == 0){
                            nx = cur.x + dx[i];
                            ny = cur.y + dy[i];
                        }
                        break;
                    case 3:
                        //cout << "maze[" << 2*cur.y-1<<"]["<<cur.x<<"]="<<maze[2*cur.y-1][cur.x]<<endl;
                        if(cur.y != 0 && maze[2*cur.y-1][cur.x] == 0){
                            nx = cur.x + dx[i];
                            ny = cur.y + dy[i];
                        }
                        break;
                    default:
                        break;
                }

                //cout << nx << "," << ny << endl;
                //cout << distance[ny][nx] << "," <<distance[cur.y][cur.x] + 1 << endl;

                if(nx+ny != -2){
                    if(distance[ny][nx] != -1){
                        if(distance[ny][nx] > distance[cur.y][cur.x] + 1){
                            distance[ny][nx] = distance[cur.y][cur.x] + 1;
                            que.push({nx,ny});
                        }
                    }else{
                        distance[ny][nx] = distance[cur.y][cur.x] + 1;
                        que.push({nx,ny});
                    }
                    nx = -1;
                    ny = -1;
                }

            }

            //cout << "-------------" << endl;

        }

/*
        for(int i=0;i<H;i++){
            for(int j=0;j<W;j++){
                cout << distance[i][j] << ",";
            }
            cout << endl;
        }
*/
        if(distance[H-1][W-1] == -1){
            cout << 0 << endl;
        }else{
            cout << distance[H-1][W-1]+1 << endl;
        }

    }


 }