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<iomanip>
#include<math.h>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<stack>
#include<set>
#include<map>
#define REP(i, N) for(ll i = 0; i < N; ++i)
#define FOR(i, a, b) for(ll i = a; i < b; ++i)
#define ALL(a) (a).begin(),(a).end()
#define pb push_back
#define INF (long long)1000000000
#define MOD 1000000007
#define EPS (long double) 1e-8
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> P;

int main() {
	while(1) {
		int w, h;
		cin>>w>>h;
		if(w == 0 && h== 0) break;
		int yoko[h][w - 1];
		int tate[h - 1][w];
		REP(i, 2 * h - 1) {
			if(i % 2 == 0) {
				REP(j, w - 1) cin>>yoko[i / 2][j];
			} else {
				REP(j, w) cin>>tate[i / 2][j];
			}
		}
		int d[h][w];
		REP(i, h) {
			REP(j, w) d[i][j] = INF;
		}
		d[0][0] = 0;
		queue<P> q;
		q.push(P(0, 0));
		while(!q.empty()) {
			P p = q.front();
			q.pop();
			if(p.first - 1 >= 0 && tate[p.first - 1][p.second] == 0 && d[p.first - 1][p.second] == INF) {
				d[p.first - 1][p.second] = d[p.first][p.second] + 1;
				q.push(P(p.first - 1, p.second));
			}
			if(p.first + 1 < h && tate[p.first][p.second] == 0 && d[p.first + 1][p.second] == INF) {
				d[p.first + 1][p.second] = d[p.first][p.second] + 1;
				q.push(P(p.first + 1, p.second));
			}
			if(p.second - 1 >= 0 && yoko[p.first][p.second - 1] == 0 && d[p.first][p.second - 1] == INF) {
				d[p.first][p.second - 1] = d[p.first][p.second] + 1;
				q.push(P(p.first, p.second - 1));
			}
			if(p.second + 1 < w && yoko[p.first][p.second] == 0 && d[p.first][p.second + 1] == INF) {
				d[p.first][p.second + 1] = d[p.first][p.second] + 1;
				q.push(P(p.first, p.second + 1));
			}
		}
		if(d[h - 1][w - 1] == INF) cout<<0<<endl;
		else cout<<d[h - 1][w - 1] + 1<<endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define MP make_pair
#define PB push_back
typedef long long ll;
bool fx[30][30],fy[30][30];
int d[30][30];
int dx[4]={0,-1,-0,1},dy[4]={1,0,-1,0};
int H,W;
int main(){
	while(cin>>W>>H&&W&&H){
		bool ok=false;
		rep(i,30)rep(j,30){
			d[i][j]=-1;
			fx[i][j]=false;
			fy[i][j]=false;
		}
		rep(i,H){
			rep(j,W-1)cin>>fx[j][i];
			if(i==H-1)break;
			rep(j,W)cin>>fy[j][i];
		}
		queue<pair<int,int> >q;
		q.push(MP(0,0));
		d[0][0]=1;
		while(!q.empty()){
			int x=q.front().first,y=q.front().second;q.pop();
			if(x==W-1&&y==H-1)ok=true;
			if(!fx[x][y]&&x+1<W&&d[x+1][y]==-1){
				q.push(MP(x+1,y));d[x+1][y]=d[x][y]+1;
			}
			if(!fy[x][y]&&y+1<H&&d[x][y+1]==-1){
				q.push(MP(x,y+1));d[x][y+1]=d[x][y]+1;
			}
			if(!fx[x-1][y]&&x-1>=0&&d[x-1][y]==-1){
				q.push(MP(x-1,y));d[x-1][y]=d[x][y]+1;
			}
			if(!fy[x][y-1]&&y-1>=0&&d[x][y-1]==-1){
				q.push(MP(x,y-1));d[x][y-1]=d[x][y]+1;
			}
		}
		if(ok)cout<<d[W-1][H-1]<<endl;
		else cout<<0<<endl;
	}
}

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

struct P
{
	int x,y,l;
};

int main(){
	int w,h;
	int dx[]={0,0,-1,1};
	int dy[]={-1,1,0,0};

	while(cin >> w >> h, w|h){

		vector< vector<bool> > map;
		vector<bool>b;

		for(int ix=0;ix<w*2-1+2;ix++)
			b.push_back(true);
		map.push_back(b);

		for(int iy=0;iy<h*2-1;iy++){
			b.clear();
			b.push_back(true);
			if(iy%2==0){
				for(int ix=0;ix<w*2-1;ix++){
					bool t=0;
					if(ix%2==1)
						cin >> t;
					b.push_back(t);
				}
			}else{
				for(int ix=0;ix<w*2-1;ix++){
					bool t=0;
					if(ix%2==0)
						cin >> t;
					b.push_back(t);
				}
			}
			b.push_back(true);
			map.push_back(b);
		}
		b.clear();
		for(int ix=0;ix<w*2-1+2;ix++)
			b.push_back(true);
		map.push_back(b);

		queue<P> que;
		que.push((P){1,1,0});
		int path=0;
		while(!que.empty()){

			P p=que.front();que.pop();
			if(p.x==w*2-1&&p.y==h*2-1){
				path=p.l+1;
				break;
			}

			/*
			cout << endl;
			for(int iy=0;iy<map.size();iy++){
				for(int ix=0;ix<map.at(iy).size();ix++)
				if(p.x!=ix||p.y!=iy)
					cout << map[iy][ix];
				else
					cout << X;
				cout << endl;
			}
			cout << endl;
			*/

			if(!(p.x+p.y))path++;
			map[p.y][p.x]==true;
			for(int i=0;i<4;i++){
				if(!map[p.y+dy[i]][p.x+dx[i]]){
					map[p.y+dy[i]][p.x+dx[i]]=true;
					que.push((P){p.x+dx[i]*2,p.y+dy[i]*2,p.l+1});
				}
			}
		}
		cout << path << endl;
	}

	return 0;
}