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++: #define MYDEBUG
#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
???
#ifdef MYDEBUG
#define debug(x) cout<<#x<<": "<<x<<endl 
#else
#define debug(x)
#endif
#define ll long long
#define ull unsigned long long
#define eps 1e-14
#define all(x) x.begin(), x.end()
using namespace std;
???
template<typename T>
ostream& operator<<(ostream& out, const vector<T>& v) {
  out << "[";
  size_t last = v.size() - 1;
  for (size_t i = 0; i < v.size(); ++i) {
    out << v[i];
    if (i != last)
      out << ",";
  }
  out << "]";
  return out;
}
???
int W,H;
const int MAXW = 30*2+1;
int cnt[MAXW][MAXW];
int ng[MAXW][MAXW];
int di[4] = {-2,0,2,0};
int dj[4] = {0,2,0,-2};
int W2,H2;
???
void bfs(int si, int sj, int gi, int gj){
	queue<int> qi;
	queue<int> qj;
	qi.push(si);
	qj.push(sj);
	while(!qi.empty()){
		int i = qi.front(), j = qj.front();
		qi.pop(); qj.pop();
		if(i==gi&&j==gj) return;
		for(int k=0; k<4; ++k){
			int ni=i+di[k], nj=j+dj[k];
			if(0<=ni&&ni<H2&&0<=nj&&nj<W2&&//???????????????????????????
			cnt[ni][nj]==0&&//????¨????(=0)????????¢?´¢
			ng[i+di[k]/2][j+dj[k]/2]==0){//???????£?????????????(i??¨i+2?????????i+2/2)
				qi.push(ni);
				qj.push(nj);
				cnt[ni][nj]=cnt[i][j]+1;
			}
		}
	}
}
???
void solve(){
	//ifstream cin("/storage/emulated/0/AppProjects/AtCoder/jni/in.txt");
	while(true){
		cin >> W >> H;
		if(W==0&&H==0) return;
		W2=2*W-1;
		H2=2*H-1;
		for(int i=0; i<MAXW; ++i){
			for(int j=0; j<MAXW; ++j){
				ng[i][j]=0;
				cnt[i][j]=0;
			}
		}
		for(int i=0; i<H; ++i){
			for(int j=0; j<W-1; j++){//v
				cin >> ng[i*2][j*2+1];
			}
			if(i==H-1) break;
			for(int j=0; j<W; j++){//h
				cin >> ng[i*2+1][j*2];
			}
		}
		bfs(0,0,H2-1, W2-1);
		int ans = cnt[H2-1][W2-1];
		if(ans>0) ans++;
		cout << ans << endl;
	}
}
???
int main() {
	solve();
}

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

int h, w, mini;
int vecX[30][30], vecY[30][30];

void solMaze(int x, int y, int sum, vector<vector<bool>> check) 
{
	if (x >= w || y >= h || x < 0 || y < 0 || check[y][x] || sum >= mini || w - x + h - y + sum >= mini) {
		return;
	}

	check[y][x] = true;

	if (y == h - 1 && x == w - 1) {
		if (sum < mini) {
			mini = sum;
		}
		return;
	}

	if (vecX[y][x] == 0) {
		solMaze(x + 1, y, sum + 1, check);
	} 
	if (x >= 1) {
		if (vecX[y][x - 1] == 0) {
			solMaze(x - 1, y, sum + 1, check);
		}
	}
	if (vecY[y][x] == 0) {
		solMaze(x, y + 1, sum + 1, check);
	}
	if (y >= 1) {
		if (vecY[y - 1][x] == 0) {
			solMaze(x, y - 1, sum + 1, check);
		}
	}

}

int main(void)
{
	vector<vector<bool>> check(30, vector<bool>(30));
	while (1) {
		mini = 1000000000;
		for (int i = 0; i < 30; ++i) {
			for (int j = 0; j < 30; ++j) {
				vecX[i][j] = 0;
				vecY[i][j] = 0;
				check[i][j] = false;
			}
		}
		cin >> w >> h;
		if (w == 0) {
			break;
		}
		for (int i = 0; i < h; ++i) {
			for (int j = 0; j < w - 1; ++j) {
				cin >> vecX[i][j];
			}
			if (i != h - 1) {
				for (int j = 0; j < w; ++j) {
					cin >> vecY[i][j];
				}
			}
 		}

 		solMaze(0, 0, 1, check);

 		if (mini == 1000000000) {
 			mini = 0;
 		}
 		cout << mini << endl;

	}

	return 0;
}

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

#define REP(i,n) for(int i=0;i<(n);i++)
#define ALL(v) (v).begin(),(v).end()
#define int long long
typedef pair<int,int> P;

//-----------------------------------------------------------------------

const int INF=1e9;
int dx[]={0,-1,0,1};
int dy[]={-1,0,1,0};
int h,w;
int bt[35][35]; // right=8,down=4,left=2,up=1

int bfs(int sy,int sx,int gy,int gx)
{
    int d[35][35];
    REP(i,h) REP(j,w) d[i][j]=INF;
    queue<P> que;
    d[sy][sx]=1;
    que.push(P(sy,sx));

    while(!que.empty()){
	int y=que.front().first;
	int x=que.front().second;
	que.pop();
	if(y==gy && x==gx) break;
	REP(i,4){
	    if(bt[y][x]>>i&1) continue;
	    int ny=y+dy[i],nx=x+dx[i];
	    if(0<=ny && ny<h && 0<=nx && nx<w && d[ny][nx]==INF){
		d[ny][nx]=d[y][x]+1;
		que.push(P(ny,nx));
	    }
	}
    }
    return (d[gy][gx]==INF?0:d[gy][gx]);
}

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

    while(cin>>w>>h,w)
    {
	REP(i,h) REP(j,w) bt[i][j]=0;
	REP(i,2*h-1){
	    if(i%2==0){
		REP(j,w-1){
		    int t; cin>>t;
		    if(!t) continue;
		    bt[i/2][j]|=8;
		    bt[i/2][j+1]|=2;
		}
	    }else{
		REP(j,w){
		    int t; cin>>t;
		    if(!t) continue;
		    bt[i/2][j]|=4;
		    bt[i/2+1][j]|=1;
		}
	    }
	}
	cout<<bfs(0,0,h-1,w-1)<<endl;
    }
}