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<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;
}

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

using namespace std;

constexpr int MAX = 30;

struct State {
    State(int x, int y, int d) 
        : x(x), y(y), depth(d) {}

    int x;
    int y;
    int depth;
};

int w, h;
int wall[MAX][MAX];

int bfs() {
    int dx[4] = {1, 0, -1, 0};
    int dy[4] = {0, 1, 0, -1};

    queue<State> que;
    que.push(State(0,0,1));

    while (!que.empty()) {
        State s = que.front();
        que.pop();

        //cout<<"("<<s.x<<","<<s.y<<")"<<endl;

        if (s.x == w - 1 && s.y == h - 1) return s.depth;

        for (int i = 0; i < 4; i++) {
            int nx = s.x + dx[i];
            int ny = s.y + dy[i];
            int from = s.x + s.y * w;
            int to = nx + ny * w;
            int depth = s.depth + 1;
            if (0 <= nx && nx < w && 0 <= ny && ny < h && !wall[from][to]) {
                que.push(State(nx, ny, depth));
            }
        }
    }
}

int main(int argc, char const *argv[]) {
    
    while (cin>>w>>h, w||h) {
        for (int i = 0; i < MAX; i++) {
            for (int j = 0; j < MAX; j++) {
                wall[i][j] = 0;
            }
        }

        for (int i = 0; i < 2 * h - 1; i++) {
            if (i % 2 == 0) {
                for (int j = 0; j < w - 1; j++) {
                    int from = i / 2 * w + j;
                    int to = from + 1;
                    int exist_wall = 0;
                    cin>>exist_wall;
                    wall[from][to] = exist_wall;
                    wall[to][from] = exist_wall;
                }
            }else {
                for (int k = 0; k < w; k++) {
                    int from = (i - 1) / 2 * w + k;
                    int to  = from + w;
                    int exist_wall = 0;
                    cin>>exist_wall;
                    wall[from][to] = exist_wall;
                    wall[to][from] = exist_wall;
                }

            }
        }

        cout<<bfs()<<endl;
    }
    return 0;
}