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>

using namespace std;

int main(){
	int w,h;

	int wallX[40][40];
	int wallY[40][40];
	int flag[40][40];

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

	while(cin>>w>>h){

		for(int i=0;i<40;i++){
			for(int j=0;j<40;j++){
				wallX[i][j]=-1;
				wallY[i][j]=-1;
				flag[i][j]=1;
			}
		}

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

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

			if(i==h)break;

			for(int j=1;j<=w;j++){
				cin>>wallY[i][j];
			}
		}

		/*
		for(int i=1;i<=h;i++){
			cout<<" ";
			for(int j=1;j<w;j++){
				if(wallX[i][j]==1){
					cout<<"| ";
				}
				else{
					cout<<"  ";
				}
			}
			cout<<endl;
			for(int j=1;j<=w;j++){
				if(wallY[i][j]==1){
					cout<<"- ";
				}
				else{
					cout<<"  ";
				}
			}
			cout<<endl;
		}
		*/


		//BFS
		queue<int> x;
		queue<int> y;
		queue<int> cnt;
		int ansFlag=0;

		x.push(1);
		y.push(1);
		cnt.push(1);
		flag[1][1]=1;

		while(x.size()!=0){
			int topX = x.front();
			int topY = y.front();
			int topCnt=cnt.front();
			x.pop();
			y.pop();
			cnt.pop();

			if(topX == w && topY ==h){
				cout<<topCnt<<endl;
				ansFlag=1;
				break;
			}

			for(int i=0;i<4;i++){
				int afterX = topX+dx[i];
				int afterY = topY+dy[i];
				if(flag[afterY][afterX] == 0){
					if(i%2==0){
						if(wallX[afterY][afterX-1]==0){
							x.push(afterX);
							y.push(afterY);
							cnt.push(topCnt+1);
							flag[afterY][afterX]=1;
						}
					}
					else{
						if(wallY[afterY-1][afterX]==0){
							x.push(afterX);
							y.push(afterY);
							cnt.push(topCnt+1);
							flag[afterY][afterX]=1;
						}
					}
				}
			}
		}
		if(ansFlag==0){
			cout<<0<<endl;
		}

	}

	return 0;
}

C++: #include <iostream>
#include <string>
#include <map>
#include <vector>
#include <algorithm>
#include <queue>

using namespace std;

const int INF = 1000000000;

int main() {
  while(1){
    int w,h;
    cin>>w>>h;
    if (!w) break;
    vector<vector<vector<int>>> graph(h, vector<vector<int>>(w));
    for (int i = 0; i < h; ++i) {
      for (int j = 0; j < w-1; ++j) {
        int f;
        cin >> f;
        if (f == 0) {
          graph[i][j].push_back(i*w+j+1);
          graph[i][j+1].push_back(i*w+j);
        }
      }
      if (i != h - 1) {
        for (int j = 0; j < w; ++j) {
          int f;
          cin >> f;
          if (f == 0) {
            graph[i][j].push_back((i+1)*w+j);
            graph[i+1][j].push_back(i*w+j);
          }
        }
      }
    }
    queue<int> q;
    q.push(0);
    vector<int> dist(w*h, INF);
    dist[0] = 1;
    while (!q.empty()) {
      int e = q.front();
      q.pop();
      int i = e / w;
      int j = e % w;
      for (int to : graph[i][j]) {
        if (dist[to] > dist[e] + 1) {
          dist[to] = dist[e] + 1;
          q.push(to);
        }
      }
    }
    if (dist[w*h-1] == INF) {
      cout << 0 << endl;
    } else {
      cout << dist[w*h-1] << endl;
    }
  }
  return 0;
}