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 <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
#include <cassert>
#include <list>
using namespace std;
static const double EPS = 1e-10;
typedef long long ll;
typedef pair<int,int> PI;
typedef vector<int> vi;
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define F first
#define S second


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

typedef struct{
  int x,y,c;
}state;

main(){
  int w,h;
  while(cin>>w>>h,w|h){
    int kabe[w][2*h-1];
    rep(i,2*h-1){
      rep(j,w+i%2-1){
        cin>>kabe[j][i];
      }
    }

    bool heya[w][h];
    memset(heya,0,sizeof(heya));

    queue<state> Q;
    Q.push((state){0,0,1});
    int ans=INT_MAX/2;

    while(!Q.empty()){
      int cx=Q.front().x,cy=Q.front().y,cc=Q.front().c;
      Q.pop();
      if(heya[cx][cy])continue;
      heya[cx][cy]=1;

      if(cx==w-1 && cy==h-1){
        ans=cc;
        break;
      }

      rep(i,4){
        int nx=cx+dx[i],ny=cy+dy[i];
        if(nx<0 || w<=nx || ny<0 || h<=ny)continue;

        if(nx==cx && kabe[nx][cy*2+dy[i]]==0){
          Q.push((state){nx,ny,cc+1});
        }else if(ny==cy && kabe[(cx+nx)/2][ny*2]==0){
          Q.push((state){nx,ny,cc+1});
        }
      }
    }
    if(ans==INT_MAX/2)cout<<0<<endl;
    else cout<<ans<<endl;
  }
}

C++: #include <iostream>
#include <queue>
#include <tuple>

#define REP(i, n) for (int i = 0; i < n; i++)
#define debug(x) cerr << #x << " = " << (x) << endl;

using namespace std;

int w, h, map[61][61];

bool check(int j, int k) {
	return (j >= 0 && j<h && k >= 0 && k <w && map[j][k] > 0);
}
/*
int dfs(int j, int k, int count){
	const int diff[]={-1, 0, 1, 0, -1};
	map[j][k] = 0;
	if ()
	count++;
	REP(i,4){
		if (check(j+diff[i],k+diff[i+1])) ans += dfs(j+diff[i], k+diff[i+1]);
	}
	return ans;
}
*/
void printmap() {
	REP(j, h) {
		REP(k, w) printf("%d ", map[j][k]);
		cout << endl;
	}
}

int main() {
	while (1) {
		int j, k, input, ans, count;
		const int diff[] = {-1, 0, 1, 0, -1};
		queue<tuple<int, int, int> > bfs;
		bool goal = false;
		// string input;
		
		cin >> w >> h;
		if (w==0 && h==0) break;

		h = h * 2 - 1;
		w = w * 2 - 1;
		ans = 0;

		REP(j, h) {
			REP(k, w) { map[j][k] = (j % 2 == 0 && k % 2 == 0) ? 1 : 0; }
		}

		REP(j, h) {
			// debug(j);
			// cin >> input;
			REP(k, w) {
				if ((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1))
					continue;
				scanf("%d", &input);
				// debug(k);
				// debug(input);
				if (input == 0) map[j][k] = 1;
			}
		}

		//printmap();

		bfs.push(make_tuple(0, 0, 1));
		map[0][0] = 0;
		
		while (!bfs.empty()) {
			j = get<0>(bfs.front());
			k = get<1>(bfs.front());
			count = get<2>(bfs.front());
			bfs.pop();
			if (j >= h - 1 && k >= w - 1) {
				cout << (count/2)+1 << endl;
				goal = true;
			}
			REP(i, 4) {
				if (check(j + diff[i], k + diff[i + 1])) {
					/*debug(j+diff[i])
					debug(k+diff[i+1]);
					debug(count);*/
					bfs.push(make_tuple(j + diff[i], k + diff[i + 1], count + 1));
					map[j+diff[i]][k+diff[i+1]] = 0;
				}
			}
		}

		// printmap();
		if (!goal) cout << 0 << endl;
	}

	return 0;
}