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 <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <utility>
#include <sstream>
#include <complex>

using namespace std;

#define FOR(i,a,b) for(long long i=(a);i<(b);i++)
#define REP(i,N) for(long long i=0;i<(N);i++)
#define ALL(s) (s).begin(),(s).end()
#define fi first
#define se second

#define PI acos(-1.0)
#define INF 1000000007
#define EPS 1e-10
#define MAX_N 20000
#define MAX_M 16

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<double, double> PD;
typedef pair<string, ll> PS;
typedef vector<ll> V;
typedef pair<P, char> PC;

int h, w, num;
int field[100][100];

int dx[] = { 1, 0, -1, 0 };
int dy[] = { 0, 1, 0, -1 };
int dx2[] = { 2, 0, -2, 0 };
int dy2[] = { 0, 2, 0, -2 };

void solve(){
	field[0][0] = 1;

	queue<P> que;
	que.push(P(0, 0));

	while (que.size()){
		P p = que.front(); que.pop();

		int y = p.first, x = p.second;

		for (int i = 0; i < 4; i++){
			int ny = y + dy2[i], nx = x + dx2[i], cy = y + dy[i], cx = x + dx[i];
			if (ny >= 0 && ny < h * 2 - 1 && nx >= 0 && nx < w * 2 - 1){
				if (field[cy][cx] != -1 && field[ny][nx] == INF){
					field[ny][nx] = field[y][x] + 1;
					que.push(P(ny, nx));
				}
			}
		}
	}

}

int main(){
	while (cin >> w >> h&&h + w){
		REP(i, 100)REP(j, 100)field[i][j] = INF;
		REP(i, 2 * h - 1){
			if (i % 2 == 0){
				REP(j, w - 1){
					cin >> num;
					if (num == 1)field[i][j * 2 + 1] = -1;
					else field[i][j * 2 + 1] = 0;
				}
			}
			else{
				REP(j, w){
					cin >> num;
					if (num == 1)field[i][j * 2] = -1;
					else field[i][j * 2] = 0;
				}
			}
		}
		solve();
		if (field[2 * h - 1 - 1][2 * w - 1 - 1] == INF)cout << 0 << endl;
		else cout << field[2 * h - 1 - 1][2 * w - 1 - 1] << endl;
	}
}

C++: // 2012/05/21 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;
				if(y==h-1)
					M[y][x] += 2;
				if(x==0)
					M[y][x] += 4;
				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;
			}
		}
		D[0][0] = 1;

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

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

/*
		for(int y=0; y<h; y++){
			for(int x=0; x<w; x++){
				cout << hex << M[y][x];
			}
			cout << endl;
		}
*/
	}

	return 0;
}