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 <queue>
#include <algorithm>
using namespace std;
typedef pair<int, int>P;
int dx[] = { 1,0,-1,0 };
int dy[] = { 0,-1,0,1 };
#define INF 100000000
int e[35][35][35][35] = { 0 };
int d[105][105] = { 0 };
int w, h;
void dfs(int x, int y) {
	if (x == h - 1 && y == w - 1) return;
	for (int i = 0; i < 4; i++) {
		int nx = x + dx[i];
		int ny = y + dy[i];
		if (0 <= nx && nx < h && 0 <= ny && ny < w && e[x][y][nx][ny] == 0) {
			if (d[nx][ny] > d[x][y] + 1) {
				d[nx][ny] = min(d[nx][ny], d[x][y] + 1);
				dfs(nx, ny);
			}
		}
	}
	return;
}

int main() {
	while (true) {
		for (int i = 0; i < 35; i++)
			for (int j = 0; j < 35; j++)
				for (int k = 0; k < 35; k++)
					for (int l = 0; l < 35; l++) e[i][j][k][l] = -1;
		
		for (int i = 0; i < 105; i++)
			for (int j = 0; j < 105; j++) d[i][j] = INF;
		cin >> w >> h;
		if (w == 0) return 0;
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w - 1; j++) {
				cin >> e[i][j][i][j + 1];
				e[i][j + 1][i][j] = e[i][j][i][j + 1];
			}
			if (i != h - 1) {
				for (int j = 0; j < w; j++) {
					cin >> e[i][j][i + 1][j];
					e[i + 1][j][i][j] = e[i][j][i + 1][j];
				}
			}
		}
		d[0][0] = 1;
		dfs(0, 0);
		if (d[h - 1][w - 1] == INF) {
			cout << 0 << endl;
		}
		else {
			cout << d[h - 1][w - 1] << endl;
		}
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
const int dy[] = { 0, 2, 0, -2 };
const int dx[] = { 2, 0, -2, 0 };
static int w;
static int h;
static int map[80][80];
int main()
{
	while (cin >> w >> h && w != 0 || h != 0)
	{
		for (int i = 0; i < 80; i++)
		{
			for (int j = 0; j < 80; j++)
			{
				map[i][j] = 0;
			}
		}

		for (int i = 0; i < h + (h - 1); i++)
		{
			for (int j = (i + 1) % 2; j < w + (w - (i + 1) % 2); j+=2)
			{
				cin >> map[i][j];
			}
		}
		int ans = 0;
		bool path[80][80];
		for (int i = 0; i < h + (h - 1); i++)
		{
			for (int j = 0; j < w + (w - 1); j++)
			{
				path[i][j] = false;
			}
		}
		queue<pair<pair<int,int>,int> >q;
		q.push(make_pair(make_pair(0, 0), 1));
		while (q.size() > 0)
		{
			pair<pair<int,int>,int> p = q.front();
			q.pop();
			path[p.first.second][p.first.first] = true;
			if (p.first.first == w + (w - 1) - 1 && p.first.second == h + (h - 1) - 1)
			{
				ans = p.second;
				break;
			}
			for (int i = 0; i < 4; i++)
			{
				int nx = p.first.first + dx[i];
				int ny = p.first.second + dy[i];
				if (nx < 0 || nx >= w + (w - 1))continue;
				if (ny < 0 || ny >= h + (h - 1))continue;
				if (map[ny][nx] == 1)continue;
				if (path[ny][nx])continue;
				int nny = p.first.second + dy[i] / 2;
				int nnx = p.first.first + dx[i] / 2;
				if (nny < 0 || nny >= h + (h - 1))continue;
				if (nnx < 0 || nnx >= w + (w - 1))continue;
				if (map[nny][nnx] == 1)continue;
				q.push(make_pair(make_pair(nx,ny),p.second + 1));
			}
		}

		cout << ans << endl;


	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
using namespace std;

typedef pair<int, int> P;
typedef pair<int, P> P2;

int W, H;

int T[30][30];
int V[30][30];

int DX[4] = {0, -1, 1, 0};
int DY[4] = {-1, 0, 0, 1};

int main() {
  while (cin >> W >> H) {
    if (W == 0 && H == 0) break;
    for (int i=0; i<H; i++) {
      for (int j=0; j<W; j++) {
        T[j][i] = 0, V[j][i] = 0;
      }
    }
    for (int i=0; i<H; i++) {
      for (int j=0; j<W-1; j++) {
        int x; cin >> x;
        if (x == 1) {
          T[j  ][i] |= 4;
          T[j+1][i] |= 2;
        }
      }
      if (i == H-1) continue;
      for (int j=0; j<W; j++) {
        int x; cin >> x;
        if (x == 1) {
          T[j][i  ] |= 8;
          T[j][i+1] |= 1;
        }
      }
    }
    queue<P2> q;
    q.push(P2(1, P(0, 0)));
    while (!q.empty()) {
      int r = q.front().first,
          x = q.front().second.first,
          y = q.front().second.second; q.pop();
      if (V[x][y] != 0) continue;
      V[x][y] = r;

      for (int k=0; k<4; k++) {
        int dx = x + DX[k], dy = y + DY[k];
        if (dx < 0 || dx >= W || dy < 0 || dy >= H) continue;
        if (T[x][y] & (1<<k)) continue;
        q.push(P2(r+1, P(dx, dy)));
      }
    }
    cout << V[W-1][H-1] << "\n";
  }
  return 0;
}