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 <iomanip>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <cfloat>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <utility>
#include <numeric>
#include <iterator>

using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int,int> PII;
typedef istringstream ISS;
typedef ostringstream OSS;

#define REP( i, m, n ) for ( int i = (int)( m ); i < (int)( n ); ++i )
#define FOR( v, c ) for ( auto &v : c )

#define EACH( it, c ) for ( auto it = c.begin(); it != c.end(); ++it )
#define ALL( c ) (c).begin(), (c).end()
#define DRANGE( c, p ) (c).begin(), (c).begin() + p, (c).end()

#define PB( n ) push_back( n )
#define MP( a, b ) make_pair( ( a ), ( b ) )
#define EXIST( c, e ) ( (c).find( e ) != (c).end() )

#define fst first
#define snd second

#define DUMP( x ) cerr << #x << " = " << ( x ) << endl
#define DEBUG( x ) cerr << __FILE__ << ":" << __LINE__ << ": " << #x << " = " << ( x ) << endl

const int INF = INT_MAX / 2;

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

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

	while ( true )
	{
		int w, h;
		cin >> w >> h;

		if ( !( w | h ) )
		{
			break;
		}

		vector<VVI> walls( h, VVI( w, VI() ) );

		REP( i, 0, 2 * h - 1 )
		{
			const int y = i / 2;
			if ( i % 2 ) // 縦方向
			{
				VI wall( w );
				FOR( tmp, wall )
				{
					cin >> tmp;
				}

				REP( i, 0, wall.size() )
				{
					if ( !wall[i] )
					{
						walls[y][i].PB( 0 );
						walls[ y + 1 ][i].PB( 2 );
					}
				}
			}
			else
			{
				VI wall( w - 1 );
				FOR( tmp, wall )
				{
					cin >> tmp;
				}

				REP( i, 0, wall.size() )
				{
					if ( !wall[i] )
					{
						walls[y][i].PB( 1 );
						walls[y][ i + 1 ].PB( 3 );
					}
				}
			}
		}

		VVI distance( h, VI( w, INF ) );
		distance[0][0] = 0;

		queue<PII> que;
		que.push( MP( 0, 0 ) );

		while ( !que.empty() )
		{
			auto cur = que.front();
			que.pop();

			FOR( d, walls[ cur.fst ][ cur.snd ] )
			{
				auto next = cur;
				next.fst += dy[d];
				next.snd += dx[d];

				if ( distance[ cur.fst ][ cur.snd ] + 1 < distance[ next.fst ][ next.snd ] )
				{
					distance[ next.fst ][ next.snd ] = distance[ cur.fst ][ cur.snd ] + 1;
					que.push( next );
				}
			}
		}

		const int res = distance.back().back();
		cout << ( res == INF ? 0 : res + 1 ) << endl;
	}

	return 0;
}

C++: //#define __USE_MINGW_ANSI_STDIO 0
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MP make_pair
#define PB push_back
#define MOD 1000000007
#define INF (1LL << 30)
#define LLINF (1LL << 60)
#define PI 3.14159265359
#define EPS 1e-12
//#define int ll
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};

int main() {
  int w, h;
  while (cin >> w >> h, w) {
    vector<vector<int>> W(2 * h - 1);
    vector<vector<int>> ret(w, vector<int>(h, 0));
    for (int i = 0; i < 2 * h - 1; ++i) {
      int j_range = i % 2 == 0 ? w - 1 : w;
      for (int j = 0; j < j_range; ++j) {
        int tmp;
        cin >> tmp;
        W[i].push_back(tmp);
      }
    }

    queue<PII> que;
    ret[0][0] = 1;
    que.push(make_pair(0, 0));
    while (!que.empty()) {
      PII p = que.front(); que.pop();
      int wy[4] = {p.second * 2 + 1, p.second * 2, p.second * 2 - 1,
                   p.second * 2},
          wx[4] = {p.first, p.first, p.first, p.first - 1};
      for (int i = 0; i < 4; ++i) {
        int nx = p.first + dx[i], ny = p.second + dy[i];
        if (0 <= nx && nx < w && 0 <= ny && ny < h && ret[nx][ny] == 0) {
          if (W[wy[i]][wx[i]] != 1) {
            que.push(make_pair(nx, ny));
            ret[nx][ny] = ret[p.first][p.second] + 1;
          }
        }
      }
    }
    cout << ret[w - 1][h - 1] << endl;
  }
}