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 <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); i++)

using namespace std;

const int inf = 1e8;

int main(){
  int H, W;
  while(cin >> W >> H, H != 0){
    int sz = (H - 1) * (W - 1);
    vector<vector<int>> g(sz, vector<int>(sz, inf));
    rep(i, sz) g[i][i] = 0;

    rep(y, H - 1) {

      rep(x, W - 1){
        int n; cin >> n;
        int l = (n == 1) ? inf : 1;
        if(y != 0){
          g[y * (W - 1) + x][(y - 1) * (W - 1) + x] = g[(y - 1) * (W - 1) + x][y * (W - 1) + x] = l;
        }
      }
      rep(x, W){
        int n; cin >> n;
        int l = (n == 1) ? inf : 1;
        if(x != 0 && x != W - 1){
          g[y * (W - 1) + x][y * (W - 1) + (x - 1)] = g[y * (W - 1) + (x - 1)][y * (W - 1) + x] = l; 
        }
      }
    }
      
    rep(x, W - 1) { int n; cin >> n; }
    /*rep(y, sz) {
        rep(x, sz){
            cout << g[y][x] << ",";
        }cout << endl;
    }*/
    rep(k, sz) rep(i, sz) rep(j, sz){
      g[i][j] = min(g[i][j], g[i][k] + g[k][j]);
    }
    int res = g[0][sz - 1] + 1;
    cout << ((res >= inf) ? 0 : res) << endl;
  }
}

C++: #include <bits/stdc++.h>
using namespace std;

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

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

//typedef
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VLL;
typedef vector<VLL> VVLL;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;

//const value
//const ll MOD = 1e9 + 7;
const int dx[] = {0,0,-1,1};
const int dy[] = {1,-1,0,0};

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

void bfs(map<PII,vector<PII>>& mp,int h,int w){

  int ci=0,cj=0;
  deque<PII> que;
  que.push_back(PII(ci,cj));

  VVI dist(h,VI(w,-1));
  dist[0][0] = 1;
  while(que.empty() == false){
    PII p = que.front();
    que.pop_front();
    ci = p.first, cj = p.second;
    for(PII np : mp[p]){
      if(dist[np.first][np.second] != -1) continue;
      dist[np.first][np.second] = dist[ci][cj] + 1;
      que.push_back(np);
    }
  }
  // rep(i,h){
  //   rep(j,w){
  //     cout << dist[i][j] << " ";
  //   }
  //   cout << endl;
  // }
  if(dist[h-1][w-1] == -1 ) cout << 0 << endl;
  else cout << dist[h-1][w-1] << endl;

}

int main(){
  int h,w;
  while(true){
    cin >> w >> h;
    if(w == 0 && h == 0 ) break;
    vector<string> b(2*h-1);
    char ch;
    rep(i,2*h-1){
      rep(j,(i%2?(w):(w-1))){
        cin >> ch;
        b[i].push_back(ch);
      }
    }

    vector<string> board(2*h-1);

    rep(i,2*h-1){
      int cnt_0 = 0;
      int cnt_1 = 0;
      rep(j,2*w-1){
        if(i%2 == 0){
          if(j%2==0) board[i].push_back('.');
          else{
            board[i].push_back(b[i][cnt_0]);
            cnt_0++;
          }
        }else{
          if(j%2==1) board[i].push_back('.');
          else board[i].push_back(b[i][cnt_1]),cnt_1++;;
        }
      }
    }

    map<PII,vector<PII> > mp;
    int gi = 0;
    int gj = 0;
    rep(i,2*h-1){
      if(i % 2 == 1) continue;
      gj = 0;
      rep(j,2*w-1){
        if(j%2==1) continue;
        rep(dir,4){
          int ni = i+dy[dir];
          int nj = j+dx[dir];
          if(ni >= 0 && nj >= 0 && ni < (2*h-1) && nj < (2*w-1) && board[ni][nj] == '0'){
            mp[PII(gi,gj)].push_back(PII(gi+dy[dir],gj+dx[dir]));
          }
        }
        gj++;
      }
      gi++;
    }
    bfs(mp, h, w);

  }
  return 0;
}