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<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<algorithm>
#include<cmath>
#include<climits>
#include<string>
#include<set>
#include<numeric>
#include<map>
#include<iostream>
using namespace std;
#define rep(i,n) for(int i = 0;i<((int)(n));i++)
#define reg(i,a,b) for(int i = ((int)(a));i<=((int)(b));i++)
#define irep(i,n) for(int i = ((int)(n)-1);i>=0;i--)
#define ireg(i,a,b) for(int i = ((int)(b));i>=((int)(a));i--)
typedef long long ll;
typedef pair<ll, ll> mp;

//?????????Memory Limit Exceeded????????£???????????????
//????????????????????£??????

//?????????
//queue??§?????????????????????visited=1
//??¨??????field=min(?????????field,??????field+1)
//??¨??????visited=0??????queue?????\?????????

//??¨???
//field[y][x]


int main(void){
	int w,h,field[30][30],visited[30][30],wall[61][30],ans[100],cnt=0,x,y;
	while(1){
		queue<int> Q;
		cin>>w>>h;
		if(w==0 && h==0)break;
		rep(i,h){
			rep(j,w){
				field[i][j]=10000;//?????¢????????????
				visited[i][j]=0;//?¨????????????????
			}
		}
		rep(i,h*2-1){
			if(i%2==0){
				rep(j,w-1)cin>>wall[i][j];
			}else if(i%2==1){
				rep(j,w)cin>>wall[i][j];
			}
		}

		//(0,0)???queue?????????
		//??????????°?????????????queue?????????????????\???????????????????????????????????????
		Q.push(0);
		Q.push(0);
		field[0][0]=1;

		while(!Q.empty()){
			x = Q.front();
			Q.pop();
			y = Q.front();
			Q.pop();
			visited[y][x]=1;
			//???????????????????????????????????????
			if(x>0 && wall[2*y][x-1]==0){//???
				if(visited[y][x-1]==0){
					Q.push(x-1);
					Q.push(y);
				}
				if(field[y][x-1]>field[y][x]+1)field[y][x-1]=field[y][x]+1;
			}
			if(x<w-1 && wall[2*y][x]==0){//???
				if(visited[y][x+1]==0){
					Q.push(x+1);
					Q.push(y);
				}
				if(field[y][x+1]>field[y][x]+1)field[y][x+1]=field[y][x]+1;
			}
			if(y>0 && wall[2*y-1][x]==0){//???
				if(visited[y-1][x]==0){
					Q.push(x);
					Q.push(y-1);
				}
				if(field[y-1][x]>field[y][x]+1)field[y-1][x]=field[y][x]+1;
			}
			if(y<h-1 && wall[2*y+1][x]==0){//???
				if(visited[y+1][x]==0){
					Q.push(x);
					Q.push(y+1);
				}
				if(field[y+1][x]>field[y][x]+1)field[y+1][x]=field[y][x]+1;
			}
		}
		if(visited[h-1][w-1]==1){
			ans[cnt]=field[h-1][w-1];
		}else{
			ans[cnt]=0;
		}
		cnt++;
	}
	rep(i,cnt)cout<<ans[i]<<endl;
	return 0;
}

C++: #include <cstdio>
#include <queue>
#include <vector>
#include <utility>

static const int di4[]={-1, 0, 1, 0};
static const int dj4[]={0, -1, 0, 1};
static const int INF=1e9;

int bfs(std::vector<std::vector<int>> maze) {
    int H=(maze.size()+1)/2, W=maze[0].size();
    std::vector<std::vector<int>> dp(H, std::vector<int>(W, INF));
    std::queue<std::pair<int, int>> q;

    dp[0][0] = 1;
    q.emplace(0, 0);

    while (!q.empty()) {
        std::pair<int, int> tmp=q.front();
        q.pop();
        int i=tmp.first, j=tmp.second;

        for (int k=0; k<4; ++k) {
            int di=di4[k], dj=dj4[k];
            if (!(0 <= i+di && i+di < H && 0 <= j+dj && j+dj < W))
                continue;

            if (dp[i+di][j+dj] <= dp[i][j] + 1) continue;
            if (maze[2*i+di][j+(dj<0? dj:0)]) continue;

            dp[i+di][j+dj] = dp[i][j] + 1;
            q.emplace(i+di, j+dj);
        }
    }

    int res=dp[H-1][W-1];
    return res<INF? res:0;
}

int solve_testcase() {
    size_t W, H;
    scanf("%zu %zu", &W, &H);

    if (H == 0 && W == 0)
        return 1;

    std::vector<std::vector<int>> maze(2*H-1, std::vector<int>(W));

    for (size_t i=0; i<maze.size(); ++i) {
        size_t j_ub=W-(i+1)%2;
        for (size_t j=0; j<j_ub; ++j)
            scanf("%d", &maze[i][j]);
    }

    printf("%d\n", bfs(maze));
    return 0;
}

int main() {
    while (!solve_testcase()) {}

    return 0;
}