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++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
void solve();
main { solve(); return 0; }
// clang-format on

void solve() {
  int w, h;
  while (cin >> w >> h, w) {
    vvi a(h, vi(w - 1)), b(h - 1, vi(w));
    rep(i, 2 * h - 1) {
      if (even(i)) rep(j, w - 1) cin >> a[i / 2][j];
      if (odd(i)) rep(j, w) cin >> b[i / 2][j];
    }
    queue<tuple<int, int, int>> q;
    q.emplace(0, 0, 1);
    vvi visited(h, vi(w));
    while (q.size()) {
      int i, j, d;
      tie(i, j, d) = q.front();
      q.pop();
      if (visited[i][j]) continue;
      visited[i][j] = true;
      if (i == h - 1 && j == w - 1) {
        cout << d << endl;
        goto next;
      }
      if (i > 0 && !b[i - 1][j]) q.emplace(i - 1, j, d + 1);
      if (j > 0 && !a[i][j - 1]) q.emplace(i, j - 1, d + 1);
      if (i < h - 1 && !b[i][j]) q.emplace(i + 1, j, d + 1);
      if (j < w - 1 && !a[i][j]) q.emplace(i, j + 1, d + 1);
    }
    cout << 0 << endl;
  next:;
  }
}

C++: #include<iostream>
#include<queue>
#include<limits.h>
using namespace std;
int dy[] = { 0, 1, 0, -1 };
int dx[] = { 1, 0, -1, 0 };
static int map[80][80];
static int minPath[80][80];
typedef struct d Data;
struct d
{
	int x;
	int y;
	int count;
};
int main()
{
	int w, h;
	while (cin >> w >> h && w != 0 || h != 0)
	{
		for (int i = 0; i < 80; i++)
		{
			for (int j = 0; j < 80; j++)
			{
				map[i][j] = 0;
			}
		}

		for (int i = 0; i < h + (h - 1); i++)
		{
			for (int j = (i + 1) % 2; j < w + (w - 1); j+=2)
			{
				cin >> map[i][j];
			}
		}
		for (int i = 0; i < h + (h - 1); i++)
		{
			for (int j = 0; j < w + (w - 1); j++)
			{
				minPath[i][j] = INT_MAX;
			}
		}

		int ans = 0;
		queue<Data> q;
		Data first;
		first.x = 0;
		first.y = 0;
		first.count = 1;
		q.push(first);
		minPath[0][0] = 1;
		while (q.size() > 0)
		{
			Data data = q.front(); q.pop();
			if (data.x == w + (w - 1) - 1 && data.y == h + (h - 1) - 1)
			{
				ans = data.count;
				break;
			}

			for (int i = 0; i < 4; i++)
			{
				int nx = data.x + dx[i] * 2;
				int ny = data.y + dy[i] * 2;
				if (nx < 0 || nx >= w + (w - 1) || ny < 0 || ny >= h + (h - 1))continue;
				int px = data.x + dx[i];
				int py = data.y + dy[i];
				if (map[py][px] == 1)continue;
				if (data.count + 1 > minPath[ny][nx])continue;
				Data d;
				d.x = nx;
				d.y = ny;
				d.count = data.count + 1;
				minPath[ny][nx] = data.count + 1;
				q.push(d);
			}
		}
		cout << ans << endl;


	}
	return 0;
}