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;

struct pos{
	int x;
	int y;
	int dis;
};

int main(){
	int w, h;
	while(cin >> w >> h){
		if(w == 0 || h == 0) break;
		int map[65][65];
		for(int i = 0; i < 65; i++){
			for(int j = 0; j < 65; j++){
				map[j][i] = 1;
			}
		}

		for(int i = 1; i <= h; i++){
			for(int j = 1; j <= w; j++){
				map[i*2-1][j*2-1] = 0;
			}
		}

		int l = 1;
		for(int i = 1; i <= h*2-1; i++){
			if(i % 2 == 1){	
				for(int j = 1; j <= w-1; j++){
					int input;
					cin >> input;
					map[l*2-1][j*2] = input;
				}
			}else{
				for(int j = 1; j <= w; j++){
					int input;
					cin >> input;
					map[l*2][j*2-1] = input;
				}
				l++;
			}
		}

		queue<pos> q;
		map[1][1] = 1;
		pos p;
		p.x = 1;
		p.y = 1;
		p.dis = 1;
		q.push(p);
		int x1[] = {-1, 0, 1, 0}, y1[] = {0, -1, 0, 1};
		while(!q.empty()){
			p = q.front();
			q.pop();
			for(int i = 0; i < 4; i++){
				pos p1 = p;
				p1.x += x1[i]; p1.y += y1[i];
				if(!map[p1.x][p1.y]){
					//p1.x += x1[i]; p1.y += y1[i];
					p1.dis++;
					map[p1.x][p1.y] = p1.dis;
					q.push(p1);
				}
 			}
		}

		int ans = (map[h*2-1][w*2-1] + 1) /2;

		cout << ans << endl;

	}
}

C++: #include <iostream>
#include <cstring>
#include <utility>
#include <queue>

using namespace std;

#define C(X,Y) (0<=(X)&&(X)<(Y))

bool can[30][30][4],vst[30][30];
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};

struct State {
	int x,y;
	int turn;
	State(int _x,int _y,int _turn);
};

State::State(int _x,int _y,int _turn)
	:x(_x),y(_y),turn(_turn) {}

int main() {
	int w,h;
	while(cin>>w>>h,w||h) {
		memset(can,0,sizeof(can));
		for(int j=0;j<h;j++) {
			for(int i=0;i<w-1;i++) {
				cin>>can[i][j][0],can[i+1][j][2]=can[i][j][0];
			}
			if(j==(h-1)) break;
			for(int i=0;i<w;i++) {
				cin>>can[i][j][1],can[i][j+1][3]=can[i][j][1];
			}
		}
		queue<State> que;
		que.push(State(0,0,1));
		memset(vst,0,sizeof(vst));
		vst[0][0]=true;
		int ans=0;
		while(!que.empty()) {
			State S(que.front());que.pop();
			if(S.x==(w-1)&&S.y==(h-1)) {ans=S.turn;break;}
			for(int i=0;i<4;i++) {
				int nx=S.x+dx[i],ny=S.y+dy[i];
				if(C(nx,w)&&C(ny,h)&&!can[S.x][S.y][i]&&!vst[nx][ny]) {
					vst[nx][ny]=true;
					que.push(State(nx,ny,S.turn+1));
				}
			}
		}
		cout<<ans<<endl;
	}
}

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