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 <algorithm>
#include <set>
#include <vector>
#include <string>
#include <queue>

using namespace std;
typedef vector<int> vi;
typedef vector<bool> vb;
int const inf = 1e9;
#define loop(i,a,b) for(int i=(a); i<int(b); i++)
#define rep(i,b) loop(i,0,b)
#define iter(it,c) for(auto it=c.begin(); it!=c.end(); ++it)
#define all(c) (c).begin(), (c).end()

typedef int Weight;
struct Edge {
    int src, dst;
    Weight weight;
    Edge(int src, int dst, Weight weight) :
        src(src), dst(dst), weight(weight) { }
};
bool operator < (const Edge &e, const Edge &f) {
    return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
    e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

typedef vector<Weight> Array;
typedef vector<Array> Matrix;

// Dijkstra法で1対多の最短経路を求める
// gは隣接リスト表現のグラフ，sは始点
// distに各頂点までの距離，prevに最短経路である頂点の1つ手前の頂点
void dijk(Graph const&g, int s, vector<Weight> &dist, vi &prev) {
    int n = g.size();
    dist.assign(n, inf); dist[s] = 0;
    prev.assign(n, -1);
    priority_queue<Edge> q; // "e < f" <=> "e.weight > f.weight"
    q.push(Edge(-2, s, 0));
    while (q.size()) {
        Edge e = q.top();
        q.pop();
        if (prev[e.dst] != -1) continue;
        prev[e.dst] = e.src;
        iter(f, g[e.dst]) {
            if (dist[f->dst] > e.weight + f->weight) {
                dist[f->dst] = e.weight + f->weight;
                q.push(Edge(f->src, f->dst, e.weight + f->weight));
            }
        }
    }
}

// 経路復元
// prevはダイクストラ法で求めた手前の頂点，tは終点
vi buildPath(vi const& prev, int t) {
    vi path;
    for (int u = t; u >= 0; u = prev[u])
        path.push_back(u);
    reverse(all(path));
    return path;
}

inline bool in(int x, int y, int h, int w){
    return 0 <= x && 0 <= y&&y < h&&x < w;
}

int main(){
    int w, h;
    while (cin >> w >> h && w | h){
        cin.ignore();
        vector<string> gs(h * 2 - 1);
        rep(i, h * 2 - 1){
            getline(cin, gs[i]);
            gs[i].resize(w * 2 - 1, ' ');
        }

        int const dx[] = { 1, 0, -1, 0 };
        int const dy[] = { 0, 1, 0, -1 };

        Graph g(h*w);
        for (int y = 0; y < gs.size(); y += 2){
            for (int x = 0; x < gs[0].size(); x += 2){
                for (int d = 0; d < 4; d++){
                    int bx = x + dx[d];
                    int by = y + dy[d];
                    if (!in(bx, by, gs.size(), gs[0].size())) continue;
                    if (gs[by][bx] == '0'){
                        int nx = bx + dx[d];
                        int ny = by + dy[d];

                        int v1 = x / 2 + y / 2 * w;
                        int v2 = nx / 2 + ny / 2 * w;
                        g[v1].push_back(Edge(v1, v2, 1));
                        g[v2].push_back(Edge(v2, v1, 1));
                    }
                }
            }
        }

        vi dist, prev;
        dijk(g, 0, dist, prev);
        int d = dist.back();
        if (d == inf) cout << 0 << endl;
        else cout << d + 1 << endl;
    }
}