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<bits/stdc++.h>
using namespace std;
const int INF = 999999;

int w, h;
int d[31][31];
int px[31][31];
int py[31][31];
queue<pair<int, int> > que;

void bfs(){
	//init rows=h, clumns=w
	/*
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++) d[i][j] = INF;
	}
	*/

	//get start point
	que.push(make_pair(0, 0));
	//init distance with start point
	d[0][0] = 1;


	//loop until queue is empty
	while(que.size()){
		int x = que.front().second;
		int y = que.front().first;
		que.pop();

		//cout << "d = " << d[y][x] << endl;
		//cout << "x = " << x << endl;
		//cout << "y = " << y << endl;

		//if x, y is goal, stop
		if(x == w - 1 and y == h - 1) break;

		//search around
		//up
		if(py[y - 1][x] == 0 and d[y - 1][x] == INF){
			que.push(make_pair(y - 1, x));
			d[y - 1][x] = d[y][x] + 1;
			//cout << "up" << endl;
		}
		//down
		if(py[y][x] == 0 and d[y + 1][x] == INF){
			que.push(make_pair(y + 1, x));
			d[y + 1][x] = d[y][x] + 1;
			//cout << "down" << endl;
		}
		//lf
		if(px[y][x - 1] == 0 and d[y][x - 1] == INF){
			que.push(make_pair(y, x - 1));
			d[y][x - 1] = d[y][x] + 1;
			//cout << "lf" << endl;
		}
		//rh
		if(px[y][x] == 0 and d[y][x + 1] == INF){
			que.push(make_pair(y, x + 1));
			d[y][x + 1] = d[y][x] + 1;
			//cout << "rh" << endl;
		}
	}

	return;
}

int main(){
while(1){//start

	int w, h;
	cin >> w >> h;
	if(w == 0 and h == 0) break;

	int idx = 0, idy = 0;
	for(int i = 0; i < 2*h - 1; i++){
		if(i % 2 == 0){
			for(int j = 0; j < w-1; j++){
				int tmp;
				cin >> tmp;
				px[idx][j] = tmp;
			}
			idx++;
		}
		else{
			for(int j = 0; j < w; j++){
				int tmp;
				cin >> tmp;
				py[idy][j] = tmp;
			}
			idy++;
		}
	}

	//init rows=h, clumns=w
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++) d[i][j] = INF;
	}

	bfs();

	/*
	//debug
	//cout << "px" << endl;
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w - 1; j++) cout << px[i][j] << " ";
		cout << endl;
	}

	cout << endl;
	//cout << "py" << endl;
	for(int i = 0; i < h - 1; i++){
		for(int j = 0; j < w; j++) cout << py[i][j] << " ";
		cout << endl;
	}
	cout << endl;

	//cout << "d" << endl;
	for(int i = 0; i < 31; i++){
		for(int j = 0; j < 31; j++) cout << d[i][j] << " ";
		cout << endl;
	}
	*/

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

}//end

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

vector<int> dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};

void bfs(vector<vector<int>> &x, vector<vector<int>> &d) {
  int h2 = x.size(), w2 = x.at(0).size();
  queue<pair<int, int>> q;
  q.push({0, 0});
  d.at(0).at(0) = 0;
  while (!q.empty()) {
    pair<int, int> p = q.front();
    q.pop();
    for (int i = 0; i < 4; i++) {
      int nr = p.first + dx[i], nc = p.second + dy[i];
      if (0 <= nr && nr < h2 && 0 <= nc && nc < w2) {
        if (x.at(nr).at(nc) == 0 && d.at(nr).at(nc) == -1) {
          d.at(nr).at(nc) = d.at(p.first).at(p.second) + 1;
          q.push({nr, nc});
        }
      }
    }
  }
  return;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  while (true) {
    int w, h;
    cin >> w >> h;
    if (w + h == 0) break;
    
    vector<vector<int>> x(2 * h - 1, vector<int>(2 * w - 1, 0));
    for (int i = 0; i < 2 * h - 1; i++) {
      for (int j = 0; j < 2 * w - 1; j++) {
        if (i % 2 == 1 && j % 2 == 1) x.at(i).at(j) = 1;
      }
    }
    
    for (int i = 0; i < 2 * h - 1; i++) {
      for (int j = 0; j < (i % 2 == 0 ? w - 1 : w); j++) {
        if (i % 2 == 0) {
          cin >> x.at(i).at(2 * j + 1);
        }
        else {
          cin >> x.at(i).at(2 * j);
        }
      }
    }
    
    vector<vector<int>> d(2 * h - 1, vector<int>(2 * w - 1, -1));
    bfs(x, d);
    
    if (d.at(2 * h - 2).at(2 * w - 2) == -1) cout << "0\n";
    else cout << d.at(2 * h - 2).at(2 * w - 2) / 2 + 1 << '\n';
  }
}