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++: #define _USE_MATH_DEFINES
#include <bits/stdc++.h>

using namespace std;

// repetition
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

// container util
#define all(x) (x).begin(), (x).end()

// debug
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                         \
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" \
       << " " << __FILE__ << endl;

// typedef
typedef long long lint;
typedef unsigned long long ull;
typedef complex<long double> Complex;
typedef pair<int, int> P;
typedef tuple<int, int, int> TP;
typedef vector<int> vec;
typedef vector<vec> mat;

// constant
const int MOD = (int)1e9 + 7;
const int INF = (int)1e18;
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
const int ddx[] = {0, 1, 1, 1, 0, -1, -1, -1};
const int ddy[] = {1, 1, 0, -1, -1, -1, 0, 1};

// conversion
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

//
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
//

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int h, w;
  while (cin >> w >> h, h || w) {
    bool board[40][40][4];
    rep(i, h) rep(j, w) rep(k, 4) board[i][j][k] = true;

    rep(i, h) board[i][0][3] = false;      // left
    rep(i, h) board[i][w - 1][1] = false;  // right
    rep(i, w) board[0][i][2] = false;      // up
    rep(i, w) board[h - 1][i][0] = false;  // down

    int in;
    rep(i, 2 * h - 1) {
      int l;
      if (i % 2 == 0)
        l = w - 1;
      else
        l = w;
      rep(j, l) {
        cin >> in;
        if (in == 1) {
          if (i % 2 == 0) {
            board[i / 2][j][1] = false;      //右に行けない
            board[i / 2][j + 1][3] = false;  //左に行けない
          } else {
            board[i / 2][j][0] = false;      //下に行けない
            board[i / 2 + 1][j][2] = false;  //上に行けない
          }
        }
      }
    }

    int dist[40][40];
    rep(i, h) rep(j, w) dist[i][j] = INF;
    dist[0][0] = 1;
    queue<P> q;
    q.push(P(0, 0));

    while (!q.empty()) {
      P t = q.front();
      q.pop();

      rep(i, 4) {
        if (!board[t.second][t.first][i]) continue;
        int x = t.first + dx[i];
        int y = t.second + dy[i];

        if (dist[y][x] <= dist[t.second][t.first] + 1) continue;
        dist[y][x] = dist[t.second][t.first] + 1;
        q.push(P(x, y));
      }
    }

    if (dist[h - 1][w - 1] == INF)
      cout << 0 << "\n";
    else
      cout << dist[h - 1][w - 1] << "\n";
  }

  return 0;
}

C++: null

C++: #include<iostream>
#include<vector>
#include<queue>
#include<cstdio>
using namespace std;

int main(){
  int w,h;
  while(cin>>w>>h,w+h){
    vector<vector<int> > wall_side(h,vector<int>(w-1));
    vector<vector<int> > wall_ud(h-1,vector<int>(w));
    vector<vector<int> > map(h,vector<int>(w,0));
    for(int i=0;i<2*h-1;i++){
      if(i%2==0){
	for(int j=0;j<w-1;j++)
	  cin>>wall_side[i/2][j];
      }else{
	for(int j=0;j<w;j++)
	  cin>>wall_ud[i/2][j];
      }
    }
    queue<int> q;
    int x=0;
    int y=0;
    q.push(y*w+x);
    map[y][x]=1;

    while(!q.empty()){
      x=q.front()%w;
      y=q.front()/w;
      q.pop();
      //up
      if(y-1>=0 && !wall_ud[y-1][x] && map[y-1][x]==0){
	q.push((y-1)*w+x);
	map[y-1][x]=map[y][x]+1;
      }
      //down
      if(y+1<h && !wall_ud[y][x] && map[y+1][x]==0){
	q.push((y+1)*w+x);
	map[y+1][x]=map[y][x]+1;
      }
      //left
      if(x-1>=0 && !wall_side[y][x-1] && map[y][x-1]==0){
	q.push(y*w+x-1);
	map[y][x-1]=map[y][x]+1;
      }
      //right
      if(x+1<w && !wall_side[y][x] && map[y][x+1]==0){
	q.push(y*w+x+1);
	map[y][x+1]=map[y][x]+1;
      }
    }
    /*
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++)
	printf("%02d ",map[i][j]);
      cout<<endl;
      }*/
    cout<<map[h-1][w-1]<<endl;

  }
  return 0;
}