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 ll=long long;
using vb=vector<bool>;
using vvb=vector<vb>;
using vd=vector<double>;
using vvd=vector<vd>;
using vi=vector<int>;
using vvi=vector<vi>;
using vl=vector<ll>;
using vvl=vector<vl>;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using tll=tuple<ll,ll>;
using tlll=tuple<ll,ll,ll>;
using vs=vector<string>;

#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define rep(i,n) range(i,0,n)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define range(i,a,n) for(int i=(a);i<(n);i++)

#define LINF ((ll)1ll<<60)
#define INF ((int)1<<30)
#define EPS (1e-9)
#define MOD (1000000007ll)
#define fcout(a) cout<<setprecision(a)<<fixed
#define fs first
#define sc second
#define PI 3.1415926535897932384

int dx[]={1,0,-1,0,1,-1,-1,1},dy[]={0,1,0,-1,1,1,-1,-1};

template<class T>bool chmax(T&a,T b){if(a<b){a=b; return true;}return false;}
template<class T>bool chmin(T&a,T b){if(a>b){a=b; return true;}return false;}
template<class S>S acm(vector<S>&a){return accumulate(all(a),S());}
template<class S>S max(vector<S>&a){return *max_element(all(a));}
template<class S>S min(vector<S>&a){return *min_element(all(a));}
void YN(bool b){cout<<(b?"YES":"NO")<<"\n";}
void Yn(bool b){cout<<(b?"Yes":"No")<<"\n";}
void yn(bool b){cout<<(b?"yes":"no")<<"\n";}

ll max(int a,ll b){return max((ll)a,b);} ll max(ll a,int b){return max(a,(ll)b);}
template<class T>void puta(T&&t){cout<<t<<"\n";}
template<class H,class...T>void puta(H&&h,T&&...t){cout<<h<<' ';puta(t...);}
template<class S,class T>ostream&operator<<(ostream&os,pair<S,T>p){os<<"["<<p.first<<", "<<p.second<<"]";return os;};
template<class S>auto&operator<<(ostream&os,vector<S>t){bool a=1; for(auto s:t){os<<(a?"":" ")<<s;a=0;} return os;}

void solve(int w,int h){
	int in;
	vvb tate(h,(vb(w-1)));
	vvb yoko(h-1,(vb(w)));
	rep(i,2*h-1){
		if(i%2==0){
			rep(j,w-1){
				cin>>in;
				tate[i/2][j]=(in==1);
			}
		}
		else{
			rep(j,w){
				cin>>in;
				yoko[i/2][j]=(in==1);
			}
		}
	}
	vvi vv(h+2,vi(w+2,-1));
	rep(i,h)rep(j,w)vv[i+1][j+1]=INF;
	vv[1][1]=1;
	queue<pii> q;
	q.push(pii(1,1));
	while(!q.empty()){
		int i,j;
		tie(i,j)=q.front();q.pop();
		if(i==h&&w==j){
			cout<<vv[i][j]<<endl;
			return;
		}
		if(vv[i][j]+1<vv[i][j+1]&&tate[i-1][j-1]==false){
			vv[i][j+1]=vv[i][j]+1;
			q.push(pii(i,j+1));
		}
		if(vv[i][j]+1<vv[i][j-1]&&tate[i-1][j-2]==false){
			vv[i][j-1]=vv[i][j]+1;
			q.push(pii(i,j-1));
		}
		if(vv[i][j]+1<vv[i+1][j]&&yoko[i-1][j-1]==false){
			vv[i+1][j]=vv[i][j]+1;
			q.push(pii(i+1,j));
		}
		if(vv[i][j]+1<vv[i-1][j]&&yoko[i-2][j-1]==false){
			vv[i-1][j]=vv[i][j]+1;
			q.push(pii(i-1,j));
		}
	}
	cout<<0<<endl;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	int h,w;
	while(cin>>w>>h,h)solve(w,h);
}

C++: #include <stdio.h>
#include "math.h"

#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <cstring>
#include <string>
#include <sstream>
#include <algorithm>
#include <iomanip>
#include <iostream>

#define VARIABLE(x) cerr << #x << "=" << x << endl
#define BINARY(x) cerr << #x << "=" << static_cast<bitset<16> >(x) << endl;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for (int i=m;i<(int)(n);i++)
#define if_range(x, y, w, h) if (0<=x && x<w && 0<=y && y<h)

const int INF = 10000000;
int dx[4]={-1, 0, 1, 0}, dy[4]={0, 1, 0, -1};
using namespace std;
typedef pair<int, int> P;

bool wall[30][30][4];
int vis[30][30];
int W, H;

void solve()
{
	queue<P> Q;
	Q.push(P(0,0));
	vis[0][0]=1;
	
	while (Q.size()) {
		P p = Q.front(); Q.pop();
		
		rep(i, 4) {
			int nx = p.first+dx[i], ny = p.second+dy[i];
			if_range(nx, ny, W, H) {
				if (vis[nx][ny]==INF) {
					if (dx[i]!=0) {
						if (!wall[nx][ny][1-dx[i]])
							Q.push(P(nx, ny));
					} else {
						if (!wall[nx][ny][2-dy[i]])
							Q.push(P(nx, ny));
					}
					vis[nx][ny]=vis[p.first][p.second]+1;
				}
			}
		}
	}
}

int main() {
	while (cin>>W>>H, W||H) {
		fill(wall[0][0], wall[0][0]+4*30*30, false);
		fill(vis[0], vis[0]+30*30, INF);
		
		rep(i, 2*H-1) {
			if (i%2==0) {
				rep(j, W-1) {
					int a; cin>>a;
					if (a) {
						wall[j][i/2][2]=true;
						wall[j+1][i/2][0]=true;
					}
				}
			} else {
				rep(j, W) {
					int a; cin>>a;
					if (a) {
						wall[j][i/2][3]=true;
						wall[j][i/2+1][1]=true;
					}
				}
			}
		}
		
		solve();
		
		cout << (vis[W-1][H-1]<INF ? vis[W-1][H-1]:0) << endl;
	}
}