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 <queue>
using namespace std;

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

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

    vector<vector<bool> > canGo(2 * h + 2, vector<bool>(2 * w + 2, false));
    for(int i = 1; i <= 2 * h; i++)
      for(int j = 1; j <= 2 * w; j++)
        canGo[i][j] = true;

    int input;
    for(int i = 1; i <= 2 * h - 1; i++){
      if(i % 2 == 1){
        for(int j = 1; j <= w - 1; j++){
          cin >> input;
          if(input == 1)
            canGo[i][j * 2 + 1] = canGo[i + 1][j * 2 + 1] = false;
        } 
      }
      else{
        for(int j = 1; j <= w; j++){
          cin >> input;
          if(input == 1)
            canGo[i][j * 2] = canGo[i][j * 2 - 1] = false;
        }
      }
    }

    int ans = 0;
    queue<pair<double, pair<int, int> > > wait;
    wait.push(make_pair(0, make_pair(1, 1)));
    canGo[1][1] = false;
    while(!wait.empty()){
      double cost = wait.front().first;
      int x = wait.front().second.first;
      int y = wait.front().second.second;
      wait.pop();
      if(x == 2 * h && y == 2 * w){
        ans = cost;
        break;
      }

      for(int i = 0; i < 4; i++){
        int nextX = x + dx[i];
        int nextY = y + dy[i];
        if(canGo[nextX][nextY]){
          wait.push(make_pair(cost + 0.5, make_pair(nextX, nextY)));
          canGo[nextX][nextY] = false;
        }
      }
    }

    cout << ans << endl;
  }

  return 0;
}

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

using namespace std;

const int MAX = 31;
const int INF = (1<<25);
int T[MAX][MAX];
int w,h;
bool edge[MAX][MAX][MAX][MAX];
int dx[] = {0,0,1,-1};
int dy[] = {1,-1,0,0};

void print(){
  for(int i = 0; i < h; i++){
    for(int j = 0; j < w; j++) cout << T[i][j] << " ";
    cout << endl;
  }
  cout << endl;
}
void init(){
  for(int i = 0; i < MAX; i++)
    for(int j = 0; j < MAX; j++)
      T[i][j] = INF;

  memset(edge,true,sizeof(edge));
}


bool inside(int x, int y){
  return 0<=x&&x<w&&0<=y&&y<h;
}
void dfs(int x, int y, int t){
  
  if(t > T[y][x]) return;

  T[y][x] = t;

  for(int i = 0; i < 4; i++){
    int nx = x+dx[i];
    int ny = y+dy[i];
    if(inside(nx,ny) && !edge[y][x][ny][nx]) dfs(nx,ny,t+1);
  }
}

int main(){
  while(cin >> w >> h && w+h){
    init();

    for(int i = 0; i < 2*h-1; i++)
      for(int j = 0; j < w-1+(i%2); j++){
	bool n;
	cin >> n;
	if(i%2) edge[i/2][j][i/2+1][j] = edge[i/2+1][j][i/2][j] = n;
	else edge[i/2][j][i/2][j+1] = edge[i/2][j+1][i/2][j] = n;
      }

    dfs(0,0,0);

    if(T[h-1][w-1] == INF) cout << "0" << endl;
    else cout << T[h-1][w-1]+1 << endl;

    //   print();
  }
  return 0;
}