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;
using pii=pair<int,int>;
using ll=long long;
using pll=pair<ll,ll>;

#define fi first
#define se second
#define pb push_back
#define rep(i,n) for(int i=0; i<(int)(n); i++)
#define MOD 1000000007

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

vector<vector<int>> G1,G2;
vector<vector<int>> dist;
int W,H;
int x[4] = {0,1,0,-1};
int y[4] = {1,0,-1,0};

void bfs() {
	queue<pii> que;
	que.push(pii(0,0));
	while(!que.empty()) {
		pii q = que.front();
		que.pop();
		//cout << q.fi << " " << q.se << endl;
		/* G[q.se][q.fi]
		isWall down: G2[q.se][q.fi]
		left: G2[q.se][q.fi-1]
		up: G2[q.se-1][q.fi]
		right: G2[q.se][q.fi]
		*/

		rep(i,4) {
			pii next = pii(q.fi + x[i], q.se + y[i]);
			//cout << next.fi << " " << next.se << endl;
			if(next.se < 0 || next.se >= H || next.fi < 0 || next.fi >= W) continue;
			if(dist[next.se][next.fi] != 1e9) continue;
			if(i == 0) {
				if(G2[q.se][q.fi]) continue;
			}
			if(i == 1) {
				if(G1[q.se][q.fi]) continue;
			}
			if(i == 2) {
				if(G2[q.se-1][q.fi]) continue;
			}
			if(i == 3) {
				if(G1[q.se][q.fi-1]) continue;
			}
			//cout << next.fi << " " << next.se << endl;
			dist[next.se][next.fi] = dist[q.se][q.fi] + 1;
			que.push(next);
		}
	}
}
int main() {
	while(1) {
		cin >> W >> H;
		if(W == 0 && H == 0) break;
		G1 = vector<vector<int>>(H, vector<int>(W));
		G2 = vector<vector<int>>(H, vector<int>(W));
		dist = vector<vector<int>>(H, vector<int>(W));
		rep(i,H) rep(j,W) dist[i][j] = 1e9;
		dist[0][0] = 1;
		rep(i,2*H-1) {
			if(i % 2 == 0) {
				rep(j,W-1) {
					cin >> G1[i/2][j];
				}
			}
			else {
				rep(j,W) {
					cin >> G2[i/2][j];
				}
			}
		}
		bfs();

		/*rep(i,H) {
			rep(j,W) {
				if(dist[i][j] == 1e9) cout << setw(3) << 0;
				else cout << setw(3) << dist[i][j];
			}
			cout << endl;
		}*/
		if(dist[H-1][W-1] == 1e9) dist[H-1][W-1] = 0;
		cout << dist[H-1][W-1] << endl;
	}

  return 0;
}

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

int main(){
	int w, h, i, j, k, c;
	
	while(1){
		int a[70][70] = {};
		cin>>w>>h;
		
		if(w == 0 && h == 0)break;
		
		
		for(i = 2; i <= w * 2; i += 2){
			a[0][i - 1] = 1;
			a[h * 2][i - 1] = 1;
		}
		
		for(j = 2; j <= h * 2; j += 2){
			a[j - 1][0] = 1;
			a[j - 1][w * 2] = 1;
		}
		
		for(i = 1; i <=  h; i++){
			for(j = 1; j < w; j++){
				cin>>a[i * 2 - 1][j * 2];
			}
			if(i != h){
				for(j = 1; j <= w; j++){
					cin>>a[i * 2][j * 2 - 1];
				}
			}
		}
		
		
		a[1][1] = 1;
		
		k = 1; c = 1;
		while(k >= 1){
			k = 0;
			for(i = 1; i < 2 * h; i +=2){
				for(j = 1; j < 2 * w; j +=2){
					if(a[i][j] == c){
						if(a[i-1][j] == 0){ if(a[i-2][j] == 0 ){ a[i-2][j] = c + 1;   k++;}}
						if(a[i+1][j] == 0){ if(a[i+2][j] == 0 ){ a[i+2][j] = c + 1;   k++;}}
						if(a[i][j+1] == 0){ if(a[i][j+2] == 0 ){ a[i][j+2] = c + 1;   k++;}}
						if(a[i][j-1] == 0){ if(a[i][j-2] == 0 ){ a[i][j-2] = c + 1;   k++;}}
					}
				}
			}
			c++;
			if(a[h * 2 - 1][w * 2 - 1] != 0) break;
		}
		
		cout<<a[h * 2 - 1][w * 2 - 1]<<endl;
	}
	
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int x[900][900],h,w,a,y[900],s;
queue<int>Q,R;
int main(){
	while(true){
		memset(x,0,sizeof(x));
		memset(y,0,3600);
		cin>>w>>h;
		if(!w){break;}
		for(int i=0;i<h*2-1;i++){
			if(i%2==1){
				for(int j=0;j<w;j++){
					cin>>a;
					if(!a){
						x[(i/2)*30+j][(i/2+1)*30+j]=1;
					}
				}
			}
			else{
				for(int j=0;j<w-1;j++){
					cin>>a;
					if(a==0){
						x[(i/2)*30+j][(i/2)*30+j+1]=1;
					}
				}
			}
		}
		Q.push(0);
		s=1;
		y[0]=1;
    	while(y[(h-1)*30+(w-1)]==0){
			while(!Q.empty()){
				a=Q.front();
				for(int j=0;j<900;j++){
					if((x[a][j]||x[j][a])&&!y[j]){
						y[j]=1;
						R.push(j);
					}
				}
				Q.pop();
			}
			while(!R.empty()){
				Q.push(R.front());
				R.pop();
			}
			s++;
			if(s>999){s=0;break;}
		}
		while(!Q.empty()){
			Q.pop();
		}
		cout<<s<<endl;
	}
}