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<cstdlib>
#include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<string>
#include<cmath>
//#include<>
using namespace std;

typedef long long int64;
typedef int int32;
typedef char int8;


#define rep(i,j) for(i=0;i<j;i++)
#define all(v) (v).begin(),(v).end()

const int INF=1<<30;//=10E10

bool bd[60][60]={};//[2h-1][2w-1]
  int w,h;
typedef struct Point
{
  int x;
  int y;
  int d;
  Point(int x_,int y_,int d_):x(x_),y(y_),d(d_){};
}Point ;

 

int solve()
{
  queue<Point> bf;
  int ans=INF;
  bf.push(Point(0,0,1));
  while(!bf.empty())
    {
      Point now=bf.front();bf.pop();
      if(bd[now.y][now.x])continue;
      else
	bd[now.y][now.x]=true;


      if(now.x==2*w-2 && now.y==2*h-2){//ゴール
	ans=now.d;
	break;
      }
      else{
	if(now.x<2*w-2&&!bd[now.y][now.x+1])bf.push(Point(now.x+2,now.y,now.d+1));
	if(now.y<2*h-2&&!bd[now.y+1][now.x] )bf.push(Point(now.x,now.y+2,now.d+1));
	if(now.x>0&& !bd[now.y][now.x-1])bf.push(Point(now.x-2,now.y,now.d+1));
	if(now.y>0&&!bd[now.y-1][now.x])bf.push(Point(now.x,now.y-2,now.d+1));
      }
      /*
      //探索の視覚化
      int i,j;
      rep(i,2*h-1)
	{
	  if(i%2==0){
	  rep(j,2*w-1)
	    if(j%2==0)cout<< (bd[i][j] ? "O" : " ");
	  cout<<endl;
	  }
	}
	  cout<<endl;
      */
    }
  if(ans==INF)ans=0;
  cout<<ans<<endl;
}

int main()
{
  while(true){
    cin>>w>>h;
    if(!w && !h)break;
    string hline,wline;
    int i,j;
    getline(cin,hline);//読み捨て
    rep(i,h-1)
      {
	getline(cin,hline);
	getline(cin,wline);
	rep(j,hline.size())
	  bd[i*2][j]= (hline[j]=='1' ? true:false);
	rep(j,wline.size())
	  bd[i*2+1][j]= (wline[j]=='1' ? true:false);
	//      cout<<"hline : "<<hline<<endl;
	//      cout<<"wline : "<<wline<<endl;
      }
    i=h-1;
    getline(cin,hline);
    rep(j,hline.size())
      bd[i*2][j]= (hline[j]=='1' ? true:false);
    
    /*
    rep(i,2*h-1)
      {
	rep(j,2*w-1)
	  cout<<bd[i][j]<<" ";
	cout<<endl;
      }
    */
 
    //探索
    solve();
  }
    return 0;
    
}

C++: #line 1 "/mnt/c/Users/leafc/dev/compro/lib/template.hpp"

#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < n; i++)
#define FOR(i, m, n) for (int i = m; i < n; i++)
#define ALL(v) (v).begin(), (v).end()
#define coutd(n) cout << fixed << setprecision(n)
#define ll long long int
#define vl vector<ll>
#define vi vector<int>

using namespace std;

#line 2 "tmp.cpp"

int main() {
  while (true) {
    int h, w;
    cin >> w >> h;
    if (h == 0 && w == 0)
      break;

    vector<vector<vector<bool>>> grid(h, vector<vector<bool>>(w, vector<bool>(4, true)));
    REP(i, 2 * h - 1) {
      if (i % 2 == 0) {
        REP(j, w - 1) {
          int t;
          cin >> t;
          if (t == 1) {
            grid[i / 2][j][0] = false;
            grid[i / 2][j + 1][2] = false;
          }
        }
      } else {
        REP(j, w) {
          int t;
          cin >> t;
          if (t == 1) {
            grid[(i - 1) / 2][j][3] = false;
            grid[(i + 1) / 2][j][1] = false;
          }
        }
      }
    }

    int dx[4] = {1, 0, -1, 0};
    int dy[4] = {0, -1, 0, 1};

    vector<vi> ans(h, vi(w, 1000));
    queue<pair<pair<int, int>, int>> q;
    q.push({{0, 0}, 1});
    while (!q.empty()) {
      auto p = q.front();
      q.pop();
      int y = p.first.first, x = p.first.second, val = p.second;
      if (ans[y][x] <= val)
        continue;
      ans[y][x] = val;

      REP(i, 4) {
        int nx = x + dx[i], ny = y + dy[i];
        if (0 <= nx && nx < w && 0 <= ny && ny < h && grid[y][x][i]) {
          if (ans[ny][nx] > val + 1)
            q.push({{ny, nx}, val + 1});
        }
      }
    }

    if (ans[h - 1][w - 1] == 1000) {
      cout << 0 << endl;
    } else {
      cout << ans[h - 1][w - 1] << endl;
    }
  }
  return 0;
}