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;

int get_index(int x,int y,int w){
  return x + y * w;
}

void add_edge(vector<vector<int>> &maze,int x1,int y1,int x2,int y2,int w){
  const int a = get_index(x1,y1,w);
  const int b = get_index(x2,y2,w);
  maze[a].emplace_back(b);
  maze[b].emplace_back(a);
}

int bfs(int s,int g,vector<vector<int>> &maze){
  const int n = maze.size();
  vector<int> d(n,-1);
  d[s] = 1;
  queue<int> q;
  q.push(s);
  while(!q.empty()){
    const int now = q.front(); q.pop();

    // can get to goal
    if(now == g) return d[now];

    for(const auto &to : maze[now]){
      if(d[to] == -1){
        d[to] = d[now] + 1;
        q.push(to);
      }
    }
  }
  // fail to get to goal
  return -1;
}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  int w,h;
  while(cin>>w>>h&&w){
    vector<vector<int>> maze(w*h);

    for(int i=0;i<h;++i){
      // vertical wall
      for(int j=0;j<w-1;++j){
        int wall; cin>>wall;
        if(!wall)
          add_edge(maze,j,i,j+1,i,w); // connect to right node
      }
      if(i==h-1) break;
      // horizontal wall
      for(int j=0;j<w;++j){
        int wall; cin>>wall;
        if(!wall){
          add_edge(maze,j,i,j,i+1,w); // connect to below node
        }
      }
    }

    const int ans = bfs(get_index(0,0,w),get_index(w-1,h-1,w),maze);
    ans == -1 ? cout<<0<<endl : cout<<ans<<endl;
  }

  return EXIT_SUCCESS; 
}

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

static const int inf = 1000;

struct node{
  int x;
  int y;
};



int hor[999][999] = {{}};
int vir[999][999] = {{}};
int pass[999][999] = {{}};
int d[999][999] = {{}};
int h,w;
node locate;
node u,t;

void bfs(int r,int s){

  queue <node> q;
 

  locate.y = r;
  locate.x = s;

  // cout << "lx = " << locate.x << ' ' << "ly = " << locate.y << endl;

  q.push(locate);

  d[0][0] = 1;

  for(int i = 0;i < h;i++){
    for(int j = 0;j < w;j++){
      pass[i][j] = 1;
    }
  }

  while(!q.empty()){
    u = q.front(); q.pop();
    if(hor[u.y][u.x] != 1 && u.y < h - 1){
      d[u.y + 1][u.x] = d[u.y][u.x] + 1;
      t.x = u.x;
      t.y = u.y + 1; 
      q.push(t);
     
    }
    if(vir[u.y][u.x] != 1 && u.x < w - 1){
      d[u.y][u.x + 1] = d[u.y][u.x] + 1;
      t.y = u.y;
      t.x = u.x + 1;
      q.push(t);
    }

    if(hor[u.y - 1][u.x] != 1 && u.y > 0){
      d[u.y - 1][u.x] = d[u.y][u.x] + 1;
      t.x = u.x;
      t.y = u.y - 1; 
      q.push(t);
     
    }

 if(vir[u.y][u.x - 1] != 1 && u.x > 0){
      d[u.y][u.x - 1] = d[u.y][u.x] + 1;
      t.y = u.y;
      t.x = u.x - 1;
      q.push(t);
    }

 // cout << "x = " << u.x << ' ' << "y = " << u.y << endl;
     if(u.x == w - 1 && u.y == h - 1) break;
  
  }





}


int main(){

  cin >> w >> h;

  for(int i =0;i < h - 1;i++){
    for(int j = 0;j < w - 1;j++) cin >> vir[i][j];
    for(int j = 0;j < w ;j++) cin >> hor[i][j];
  }

   for(int j = 0;j < w - 1;j++) cin >> vir[h - 1][j];


   bfs(0,0);

   cout << d[h - 1][w - 1] << endl;

}