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 <string>
#include <vector>
#include <queue>
using namespace std;

int map[100][100] = {};
int w, h;

void reset(){
	for(int i = 0;i<100;i++){
		for(int j = 0;j<100;j++){
			map[i][j] = 0;
		}
	}
}

int main(){
	while(cin >> w >> h){
		if (!w && !h) break;
		reset();
		for(int i = 0;i<2 * h -1;i++){
			if (i % 2 == 0) {
				for (int j = 0; j < w - 1; j++) {
					cin >> map[i][2 * j + 1];
				}
			}
			else {
				for (int j = 0; j < w; j++) {
					cin >> map[i][2 * j];
				}
			}
		}
		queue<pair<int, int>> que;
		que.push(pair<int, int>(0, 0));
		int n = 0;
		while(que.size()){
			int que_size = que.size();
			for(int x = 0;x<que_size;x++){
				pair<int, int> now = que.front();
				que.pop();
				map[now.first * 2][now.second * 2] = n;
				if( now.first < h-1 && map[now.first * 2 + 1][now.second * 2] == 0 && map[(now.first + 1) * 2][now.second * 2] == 0){
					que.push(pair<int, int>(now.first + 1, now.second));
				}
				if (now.first > 0 && map[now.first * 2 - 1][now.second * 2] == 0 && map[(now.first - 1) * 2][now.second * 2] == 0) {
					que.push(pair<int, int>(now.first - 1, now.second));
				}
				if (now.second < w-1 && map[now.first * 2][now.second * 2 + 1] == 0 && map[now.first * 2][(now.second + 1) * 2] == 0) {
					que.push(pair<int, int>(now.first, now.second + 1));
				}
				if (now.second > 0 && map[now.first * 2][now.second * 2 - 1] == 0 && map[now.first * 2][(now.second - 1) * 2] == 0) {
					que.push(pair<int, int>(now.first, now.second - 1));
				}
			}
			n++;
		}
		if(map[(h - 1) * 2][(w - 1) * 2] != 0) cout << map[(h-1) * 2][(w-1) * 2]  + 1 << endl;
		else cout << 0 << endl;
	}
	return 0;
}

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

#define rep(i,n) for(int i=0;i<(int)n;++i)
#define SZ(a) (int)((a).size())
#define mp make_pair
#define pb push_back
#define F first
#define S second
typedef pair<int,int> PI;
int dx[] = {0,1,0,-1};
int dy[] = {-1,0,1,0};

int w,h;
int mei[100][100];
void solve(){
  //cout << w << h << endl;
  memset(mei,0,sizeof(mei));
  
  rep(i,100)rep(j,100) mei[i][j]=i%2 && j%2;
  int cnt = 0;
  
  rep(i,h*2-1){
    rep(j,w-(~i&1)){
      //cout <<w-(~i&1) << endl;
      ++cnt;
      int t;
      cin >> t;
      if(i&1) mei[i][j*2] = t;
      else mei[i][j*2+1] = t;
    }
  }
  //cout << cnt << endl;

  

  queue<pair<int,PI> > q;
  q.push(mp(0,mp(0,0)));
  
  while(!q.empty()){
    int cc = q.front().F;
    int cx = q.front().S.F;
    int cy = q.front().S.S;

    q.pop();
    if(cx >= h*2 || cy >= w*2 || cx<0 || cy < 0) continue;    
    if(mei[cx][cy]) continue;
    mei[cx][cy]  = 1;
    
    if( cx == h*2-2 && cy == w*2-2){
      cout << cc/2 +1<< endl;
      return;
    }
    rep(i,4) q.push(mp(cc+1,mp(cx+dx[i],cy+dy[i])));
  }
  
  cout << 0 << endl;
}

int main(){
  while(cin >> w >> h,w) solve();
}

C++: #include <cstdio>
#include <algorithm>

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

using namespace std;

const int INF=1<<29;
const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};

int main(){
	for(int h,w;scanf("%d%d",&w,&h),h;){
		int hor[50][50],ver[50][50];
		rep(i,h){
			rep(j,w-1) scanf("%d",ver[i]+j);
			if(i<h-1){
				rep(j,w) scanf("%d",hor[i]+j);
			}
		}

		int d[50][50];
		rep(i,h) rep(j,w) d[i][j]=INF;
		d[0][0]=1;
		rep(_,h*w){
			rep(i,h) rep(j,w) rep(k,4) {
				int y=i+dy[k],x=j+dx[k];
				if(k==0 && ver[ i ][ j ]==0
				|| k==1 && hor[i+1][ j ]==0
				|| k==2 && ver[ i ][j-1]==0
				|| k==3 && hor[ i ][ j ]==0) d[y][x]=min(d[y][x],d[i][j]+1);
			}
		}
		printf("%d\n",d[h-1][w-1]<INF?d[h-1][w-1]:0);
	}

	return 0;
}