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 "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "iomanip"
#include "cmath"

using namespace std;

const long long int MOD = 1000000007;

long long int N, M, K, H, W, L, R;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> W >> H;
	while (H) {
		vector<vector<int>>edge(H*W);
		vector<int>dis(H*W, INT_MAX);
		dis[0] = 0;
		string s;
		getline(cin, s);
		for (int i = 0; i < H * 2 - 1; i++) {
			getline(cin, s);
			if (i % 2) {
				for (int j = 0; j < W*2-1; j += 2) {
					if (s[j] == '0') {
						//cout << (i / 2)*W + j / 2 << " " << (i / 2 + 1)*W + j / 2 << endl;
						edge[(i / 2)*W + j / 2].push_back((i / 2 + 1)*W + j / 2);
						edge[(i / 2 + 1)*W + j / 2].push_back((i / 2)*W + j / 2);
					}
				}
			}
			else {
				for (int j = 1; j < W*2-1; j += 2) {
					if (s[j] == '0') {
						//cout << (i / 2)*W + j / 2 << " " << (i / 2)*W + j / 2 + 1 << endl;
						edge[(i / 2)*W + j / 2].push_back((i / 2)*W + j / 2 + 1);
						edge[(i / 2)*W + j / 2 + 1].push_back((i / 2)*W + j / 2);
					}
				}
			}
		}
		queue<int>Q;
		Q.push(0);
		while (!Q.empty()) {
			int cn = Q.front();
			//cout << cn << endl;
			Q.pop();
			for (auto i : edge[cn]) {
				//cout << " " << i << endl;
				if (dis[i] > dis[cn] + 1) {
					dis[i] = dis[cn] + 1;
					Q.push(i);
				}
			}
		}
		if (dis[H*W - 1] == INT_MAX) {
			cout << 0 << endl;
		}
		else {
			cout << dis[H*W - 1] + 1 << endl;
		}
		cin >> W >> H;
	}
	return 0;
}

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;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<pii> vpii;
typedef vector<vi> vvi;
typedef vector<vb> vvb;
typedef vector<vpii> vvpii;
const int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
const int MOD = 1000000007;
const 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; }
bool odd(const int &n) { return n & 1; }
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:;
  }
}