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 <vector>
#include <string>
#include <queue>

using namespace std;

typedef pair<int, int> lo;
int h, w;

int bfs(vector<vector<int> > maze) {
	vector<vector<int> > dist(h * 2 + 3, vector<int>(w * 2 + 3, 1));
	int dix[] = { -2,0,0,2 }, diy[] = { 0,-2,2,0 };
	int ddix[] = { -1,0,0,1 }, ddiy[] = { 0,-1,1,0 };
	queue<lo> que;
	que.push(make_pair(2, 2));
	while (!que.empty()) {
		lo q = que.front(); que.pop();
		for (int i = 0; i < 4; ++i) {
			if (q.first == h * 2 && q.second == w * 2) return dist[q.first][q.second];
			int xtmp = q.first + dix[i], ytmp = q.second + diy[i];
			if (maze[xtmp - ddix[i]][ytmp - ddiy[i]] == 0 && maze[xtmp][ytmp] == 0 && dist[xtmp][ytmp] == 1) {
				dist[xtmp][ytmp] = dist[q.first][q.second] + 1;
				que.push(make_pair(xtmp, ytmp));
			}
		}
	}
	return 0;
}

int main() {
	while (cin >> w >> h && w) {
		vector<vector<int> > maze(h * 2 + 3, vector<int>(w * 2 + 3, 1));
		maze[2][2] = 0; maze[h * 2][w * 2] = 0;
		cin.ignore();
		string s;
		for (int i = 2; i < h * 2 + 1; ++i) {
			getline(cin, s);
			for (int j = 2; j < w * 2 + 1; ++j) {
				if (s[j - 2] == ' ' || s[j - 2] == '\0') maze[i][j] = 0;
				else maze[i][j] = s[j - 2] - '0';
				if (maze[i][j] == 1) {
					if (i % 2) maze[i][j - 1] = 1;
					else maze[i - 1][j] = 1;
				}
			}
		}

		cout << bfs(maze) << endl;
	}

	return 0;
}

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

using namespace std;

// →　↓　←　↑
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

class state {
public:
    int x, y, d;
    state(int a, int b, int c) { x = a; y = b; d = c; }
};

int main()
{
    int h, w;

    while (cin >> w >> h, w || h) {
        bool flag = false;
        int maze[32][32][4] = {0};
        bool past[32][32] = {false};
        int inp;

        memset(maze, 0, sizeof(maze));
        memset(past, 0, sizeof(past));
        // Input
        for (int y = 0; y < h; y++) {
            for (int x = 0; x < w - 1; x++) {
                cin >> maze[y][x][0];
                maze[y][x + 1][2] = maze[y][x][0];
            }

            if (y < h - 1) 
                for (int x = 0; x < w; x++) {
                    cin >> maze[y][x][1];
                    maze[y + 1][x][3] = maze[y][x][1];
                }
        }
        
        state s(0, 0, 1);
        queue<state> q;
        q.push(s);
        
        while (!q.empty()) {
            state now = q.front();
            q.pop();
            past[now.y][now.x] = true;
            
            if (now.x == w - 1 && now.y == h - 1) {
                cout << now.d << endl;
                flag = true;
                break;
            }

            for (int i = 0; i < 4; i++) {
                if (maze[now.y][now.x][i] == 1)
                    continue;
                int nx = now.x + dx[i];
                int ny = now.y + dy[i];

                if (nx < 0 || ny < 0 || nx >= w || ny >= h)
                    continue;

                if (past[ny][nx] == false)
                    q.push(state(nx, ny, now.d + 1));
            }
        }

        if (!flag)
            cout << 0 << endl;
    }

    return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
#define rep(i, n) for ( int i = 0; i < n; i++)
struct Point{int y, x;};

int W[100][50], w, h;

int bfs(){
  Point s;
  s.y = s.x = 0;
  queue<Point> Q;
  int d[50][50];
  rep(i, h) rep(j, w) d[i][j] = (1<<21);
  d[0][0] = 1;
  Q.push(s);
  Point u, v;
  int dy[4] = {0, -1, 0, 1};
  int dx[4] = {1, 0, -1, 0};
  int ny, nx, ii, jj;

  while(!Q.empty()){
    u = Q.front(); Q.pop();
    if ( u.y == h-1 && u.x == w-1 ) return d[u.y][u.x];
    rep(r, 4){
      nx = u.x + dx[r];
      ny = u.y + dy[r];
      if ( nx < 0 || ny < 0 || ny >= h || nx >= w || d[ny][nx] != (1<<21)) continue;
      if ( W[u.y*2+dy[r]][u.x-((r==2)?(1):0)] )	continue;
      d[ny][nx] = d[u.y][u.x] + 1;
      v.x = nx;
      v.y = ny;
      Q.push(v);
    }
  }

  return 0;
}

main(){
  while(cin>> w >> h && (w&&h)){
    rep(i, h*2-1) rep(j, ((i%2)?w:w-1)) cin >> W[i][j];
    cout << bfs() << endl;
  }
}