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>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) range(i,0,b)
#define itrep(it, a) for(it = (a).begin(); it != (a).end; it++)
#define all(a) (a).begin(), (a).end()
#define debug(x) cout << "debug " << x << endl;
#define INF (1 << 30)
using namespace std;

#define N 35

struct point{ int x, y; };
int dy[4] = {0,1,0,-1}, dx[4] = {1,0,-1,0};

int bfs(bool M[N][N], int h, int w){
    int dis[N][N];
    queue<point> q;
    rep(i,N) rep(j,N) dis[i][j] = INF;
    point a;
    a.x = 2;
    a.y = 0;

    dis[0][2] = 0;
    q.push(a);

    point u;
    while(!q.empty()){
        u = q.front(); q.pop();
        rep(i,4){
            point next;
            next.x = u.x + dx[i];
            next.y = u.y + dy[i];
            if(M[next.y][next.x] != 1 && dis[next.y][next.x] == INF){
                dis[next.y][next.x] = dis[u.y][u.x] + 1;
                q.push(next);
            }
        }
    }
    return dis[h + h - 1][w + w] + 1;
}

void printMaze(int h, int w, bool M[N][N]){
    rep(i,h + h - 1){
        rep(j,w + w + 1){
            cout << M[i][j];
        }
        cout << endl;
    }
}

int main(){
    /*
    10101
    10111
    10001
    11101
    10101
    */
    int w, h;
    while(cin >> w >> h, w||h){
        bool M[N][N] = {0};
        rep(i,N) rep(j,N) M[i][j] = 1;
        rep(i,h + h - 1){
            if(i % 2){
                for(int j = 0; j <= w + w; j++){
                    if(j == 0 || j == w + w) M[i + 1][j + 1] = 1;
                    else if(j % 2 == 0) M[i + 1][j + 1] = 1;
                    else cin >> M[i + 1][j + 1];
                }
            }else{
                for(int j = 0; j <= w + w; j++){
                    if(j == 0 || j == w + w) M[i + 1][j + 1] = 1;
                    else if(j % 2 == 1) M[i + 1][j + 1] = 0;
                    else cin >> M[i + 1][j + 1];
                }
            }
        }
        long long ans = bfs(M,h,w);
        if(ans > 20000) cout << 0 << endl;
        else cout << ans / 2 << endl;
        //printMaze(h + 1,w + 1,M);
    }
}

C++: #include <stdio.h>
#define INF 10000000
//#define DEBUG
int map[100][100];
int dp[100][100];
int w,h;

int walk(int x,int y,int step){
	dp[x][y]=step;
	//printf("walk %d %d %d\n",x,y,step);
	if(x-1>-1&&map[y*2][x-1]!=1&&dp[x-1][y]>step+1)walk(x-1,y,step+1);
	if(x+1<w&&map[y*2][x]!=1&&dp[x+1][y]>step+1)walk(x+1,y,step+1);
	if(y-1>-1&&map[y*2-1][x]!=1&&dp[x][y-1]>step+1)walk(x,y-1,step+1);
	if(y+1<h&&map[y*2+1][x]!=1&&dp[x][y+1]>step+1)walk(x,y+1,step+1);
	return 0;
}


int main(void){
	int i,j,k;
	while(scanf("%d %d",&w,&h),(w||h)){
		for(i=0;i<w;i++){
			for(j=0;j<h;j++){
				dp[i][j]=INF;
			}
		}
		for(i=0;i<2*h-1;i++){
			if(i%2==0) j=w-1;
			else j=w;
			for(k=0;k<j;k++){
				scanf("%d",&map[i][k]);
			}
		}
#ifdef DEBUG
		printf("mapmake:\n");
		for(i=0;i<2*h-1;i++){
			for(j=0;j<w;j++){
				printf("%d ",map[i][j]);
			}
			printf("\n");
		}
#endif
		walk(0,0,1);
#ifdef DEBUG
		printf("listmake:\n");
		for(i=0;i<h;i++){
			for(j=0;j<w;j++){
				if(dp[j][i]!=INF)printf("%d ",dp[j][i]);
				else printf("N ");
			}
			printf("\n");
		}
		printf("answer:\n");
#endif
	if(dp[w-1][h-1]==INF) printf("0\n");
	else printf("%d\n",dp[w-1][h-1]);
	}
	return 0;
}