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 <cstdio>
#include <string>
#include <vector>
#include <stack>
#include <deque>
#include <queue>
#include <set>
#include <cmath>
#include <algorithm>
//#include <map>

using namespace std;

#define MAX 1024
typedef pair<int, int> P;

int main(void) {
	while(1) {
		queue<P> qpoint;
		int map[30][30];
		int len[30][30];
		int w, h;
		int x, y, xx, yy;
		const int dx[4] = {0, 1, 0, -1}, dy[4] = {-1, 0, 1, 0};

		scanf("%d %d", &w, &h);
		if(!w && !h) break;
		for(int i = 0; i < h*2-1; i++) {
			if(i % 2) {
				for(int j = 0; j < w; j++) {
					scanf("%d", &map[i][j]);
				}
			} else {
				for(int j = 0; j < w - 1; j++) {
					scanf("%d", &map[i][j]);
				}
			}
		}
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				len[i][j] = MAX;
			}
		}
		qpoint.push(P(0, 0));
		len[0][0] = 1;
		while(qpoint.size()) {
			x = qpoint.front().first;  y = qpoint.front().second;
			qpoint.pop();
			if(x == w-1 && y == h-1) break;
			for(int i = 0; i < 4; i++) {
				xx = x + dx[i];  yy = y + dy[i];
				if(0 <= xx && xx < w && 0 <= yy && yy < h && len[y][x] + 1 < len[yy][xx]) {
					if(i == 0 && map[2*yy+1][xx] == 1) continue;
					if(i == 1 && map[2*yy][xx-1] == 1) continue;
					if(i == 2 && map[2*yy-1][xx] == 1) continue;
					if(i == 3 && map[2*yy][xx] == 1) continue;
					qpoint.push(P(xx, yy));
					len[yy][xx] = len[y][x] + 1;
				}
			}
		}
		printf("%d\n", len[h-1][w-1] == MAX ? 0 : len[h-1][w-1]);
	}
	return 0;
}

C++: // Tazoe

#include <iostream>
using namespace std;

void DFS(const int M[30][30], int D[30][30], int Y, int X, int C)
{
	D[Y][X] = C;

	if(M[Y][X]%2==0&&D[Y-1][X]>C+1){
		DFS(M, D, Y-1, X, C+1);
	}

	if(M[Y][X]/2%2==0&&D[Y+1][X]>C+1){
		DFS(M, D, Y+1, X, C+1);
	}

	if(M[Y][X]/4%2==0&&D[Y][X-1]>C+1){
		DFS(M, D, Y, X-1, C+1);
	}

	if(M[Y][X]/8%2==0&&D[Y][X+1]>C+1){
		DFS(M, D, Y, X+1, C+1);
	}
}

int main()
{
	while(true){
		int w, h;
		cin >> w >> h;

		if(w==0&&h==0)
			break;

		int M[30][30];
		for(int y=0; y<h; y++){
			for(int x=0; x<w; x++){
				M[y][x] = 0;

				if(y==0){
					M[y][x] += 1;
				}
				else if(y==h-1){
					M[y][x] += 2;
				}

				if(x==0){
					M[y][x] += 4;
				}
				else if(x==w-1){
					M[y][x] += 8;
				}
			}
		}

		for(int i=0; i<2*h-1; i++){
			if(i%2==0){
				for(int j=0; j<w-1; j++){
					int w;
					cin >> w;

					if(w==1){
						M[i/2][j]   += 8;
						M[i/2][j+1] += 4;
					}
				}
			}
			else{
				for(int j=0; j<w; j++){
					int w;
					cin >> w;

					if(w==1){
						M[i/2][j]   += 2;
						M[i/2+1][j] += 1;
					}
				}
			}
		}

		int D[30][30];
		for(int y=0; y<h; y++){
			for(int x=0; x<w; x++){
				D[y][x] = 1000;
			}
		}

		DFS(M, D, 0, 0, 1);

		if(D[h-1][w-1]!=1000){
			cout << D[h-1][w-1] << endl;
		}
		else{
			cout << 0 << endl;
		}
	}

	return 0;
}