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>
#define rep(i, n) for(int i = 0; i < (n); i++)

using namespace std;

const int inf = 1e8;

int main(){
  int H, W;
  while(cin >> W >> H, H != 0){
    int sz = H* W;
    vector<vector<int>> g(sz, vector<int>(sz, inf));
    rep(i, sz) g[i][i] = 0;

    rep(y, H) {

      rep(x, W - 1){
        int n; cin >> n;
        int l = (n == 1) ? inf : 1;
          g[y * W + x][y * W + (x + 1)] = g[y * W + (x + 1)][y * W + x] = l; 
      }
      if(y == H - 1) break;
      rep(x, W){
        int n; cin >> n;
        int l = (n == 1) ? inf : 1;
          g[y * W + x][(y + 1) * W + x] = g[(y + 1) * W + x][y * W + x] = l;
        
      }
    }
      
   
    vector<vector<int>> a(sz);
    rep(i, sz){
       rep(j, sz){
           if(g[i][j] == 1) a[i].push_back(j);
       }
    }
    
    deque<tuple<int, int>> q;
    vector<int> vis(sz, inf);
    vis[0] = 0;
    q.emplace_back(0, 0);
    while(q.size() > 0){
      int h, s; tie(h, s) = q.back(); q.pop_back();
      for(auto&& k : a[h]){
          if(vis[k] == inf){
              vis[k] = s + 1;
              q.emplace_back(k, s + 1);
          }
      }
    }
    int res = vis[sz - 1] + 1;
    cout << ((res >= inf) ? 0 : res) << endl;
  }
}

C++: #include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
#define INF 0x3f3f3f3f
using namespace std;
typedef pair<int, int>P;

int d[50][50];
int dx[]{ 1,-1,0,0 }, dy[]{ 0,0,1,-1 };
int main() {
	int w, h;
	while (scanf("%d%d", &w, &h), w) {
		vector<pair<P, P>>wall;
		rep(i, 2 * h - 1) {
			if (i & 1) {
				rep(j, w) {
					int d; scanf("%d", &d);
					if (d) {
						wall.push_back({ {i / 2 ,j},{i / 2 + 1,j} });
						wall.push_back({ { i / 2 + 1,j },{ i / 2 ,j } });
					}
				}
			}
			else {
				rep(j, w - 1) {
					int d; scanf("%d", &d);
					if (d) {
						wall.push_back({ {i / 2,j},{i / 2,j + 1} });
						wall.push_back({ { i / 2,j + 1 },{ i / 2,j } });
					}
				}
			}
		}
		sort(wall.begin(), wall.end());
		queue<P>que;
		memset(d, 0x3f, sizeof(d));
		que.push(P(0, 0));
		d[0][0] = 1;
		while (!que.empty()) {
			P p = que.front(); que.pop();
			if (p.first == h - 1 && p.second == w - 1)break;
			rep(i, 4) {
				int nx = p.first + dx[i], ny = p.second + dy[i];
				if (0 <= nx&&nx < h && 0 <= ny&&ny < w&&d[nx][ny] == INF && !binary_search(wall.begin(), wall.end(), make_pair(p, P(nx, ny)))) {
					que.push(P(nx, ny));
					d[nx][ny] = d[p.first][p.second] + 1;
				}
			}
		}
		printf(d[h - 1][w - 1] == INF ? "0\n" : "%d\n", d[h - 1][w - 1]);
	}
}

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

#define INF (1 << 29)

using namespace std;

const int dx[4] = { 0, 1, 0, -1 };
const int dy[4] = { -1, 0, 1, 0 };

int main()
{
	int H, W, T; vector<vector<vector<bool> > > M;

	while (true)
	{
		cin >> W >> H;

		if (W == 0 && H == 0) { break; }

		M = vector<vector<vector<bool> > >(H, vector<vector<bool> >(W, vector<bool>(4, false)));

		for (int i = 0; i < W; i++)
		{
			M[0][i][0] = true;
		}

		for (int i = 0; i < H; i++)
		{
			M[i][W - 1][1] = true;
		}

		for (int i = 0; i < W; i++)
		{
			M[H - 1][i][2] = true;
		}
		
		for (int i = 0; i < H; i++)
		{
			M[i][0][3] = true;
		}

		for (int i = 0; i < 2 * H - 1; i++)
		{
			for (int j = 0; j < (i % 2 == 0 ? W - 1 : W); j++)
			{
				cin >> T;

				if (T == 1)
				{
					if (i % 2 == 0)
					{
						M[i / 2][j][1] = true;
						M[i / 2][j + 1][3] = true;
					}
					else
					{
						M[i / 2][j][2] = true;
						M[i / 2 + 1][j][0] = true;
					}
				}
			}
		}

		vector<vector<int> > dp(H, vector<int>(W, INF)); dp[0][0] = 1;

		queue<pair<int, int> > que; que.push(make_pair(0, 0));

		while (!que.empty())
		{
			pair<int, int> p1 = que.front(); que.pop();

			int x = p1.first;
			int y = p1.second;

			for (int dir = 0; dir < 4; dir++)
			{
				if (M[y][x][dir] == false)
				{
					if (dp[y + dy[dir]][x + dx[dir]] == INF)
					{
						dp[y + dy[dir]][x + dx[dir]] = dp[y][x] + 1;

						que.push(make_pair(x + dx[dir], y + dy[dir]));
					}
				}
			}
		}

		if (dp[H - 1][W - 1] == INF)
		{
			cout << 0 << endl;
		}
		else
		{
			cout << dp[H - 1][W - 1] << endl;
		}
	}

	return 0;
}