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;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=n-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define at(x,i) get<i>(x);
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={1,0,-1,0,1,1,-1,-1};
const ll dx[8]={0,-1,0,1,1,-1,1,-1};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
int main(){
    while(true){
    ll h,w;cin >> w >>h;
    if(w==0&&h==0)break;
    vvl lr(h,vl(w-1)),ud(h-1,vl(w));
    rep(i,2*h-1){
        if(i%2==0){
            rep(j,w-1)cin >> lr[i/2][j];
        }
        else{
            rep(j,w)cin >> ud[(i-1)/2][j];
        }
    }
    queue<pl> que;
    que.push(mp(0,0));
    vvl dist(h,vl(w,0));
    dist[0][0]=1;
    while(!que.empty()){
        pl v=que.front();
        que.pop();
        rep(i,4){
            ll ny=v.fi+dy[i],nx=v.se+dx[i];
            if(ny<0||nx<0||ny>=h||nx>=w)continue;
            if(dist[ny][nx]!=0)continue;
            if(i==0&&ud[v.fi][nx]==1)continue;
            if(i==1&&lr[ny][nx]==1)continue;
            if(i==2&&ud[ny][nx]==1)continue;
            if(i==3&&lr[ny][v.se]==1)continue;
            dist[ny][nx]=dist[v.fi][v.se]+1;
            que.push(mp(ny,nx));
        }
    }
    cout << dist[h-1][w-1] <<endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
int w, h;
int r[31][31], u[31][31];
int a[31][31];
deque<pair<int, int> > Q;
pair<int, int> x, y;
int main()
{
	while(cin >> w >> h && w>0)
	{
		for(int i=0; i<h; i++)
		{
			for(int j=0; j<w; j++)
			{
				a[i][j]=-1;
			}
		}
		for(int i=0; i<h-1; i++)
		{
			for(int j=0; j<w-1; j++)
			{
				cin >> r[i][j];
			}
			for(int j=0; j<w; j++)
			{
				cin >> u[i][j];
			}
		}
		for(int j=0; j<w-1; j++)
		{
			cin >> r[h-1][j];
		}
		Q.clear();
		x=make_pair(0, 0);
		Q.push_back(x);
		a[0][0]=1;
		while(!Q.empty())
		{
			x=Q.front();
			Q.pop_front();
			if(x.first!=0)
			{
				if((u[x.first-1][x.second]==0)&&(a[x.first-1][x.second]==-1))
				{
					y=make_pair(x.first-1, x.second);
					Q.push_back(y);
					a[x.first-1][x.second]=a[x.first][x.second]+1;
				}
			}
			if(x.second!=0)
			{
				if((r[x.first][x.second-1]==0)&&(a[x.first][x.second-1]==-1))
				{
					y=make_pair(x.first, x.second-1);
					Q.push_back(y);
					a[x.first][x.second-1]=a[x.first][x.second]+1;
				}
			}
			if(x.first!=h-1)
			{
				if((u[x.first][x.second]==0)&&(a[x.first+1][x.second]==-1))
				{
					y=make_pair(x.first+1, x.second);
					Q.push_back(y);
					a[x.first+1][x.second]=a[x.first][x.second]+1;
				}
			}
			if(x.second!=w-1)
			{
				if((r[x.first][x.second]==0)&&(a[x.first][x.second+1]==-1))
				{
					y=make_pair(x.first, x.second+1);
					Q.push_back(y);
					a[x.first][x.second+1]=a[x.first][x.second]+1;
				}
			}
		}
		if(a[h-1][w-1]==-1)
		{
			cout << 0 << endl;
		}
		else
		{
			cout << a[h-1][w-1] << endl;
		}
	}
	return 0;
}