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 ll = long long;
using namespace std;
#define rep(i,n) for(int i=0, i##_len=(int)(n); i<i##_len; i++)
#define reps(i,n) for(int i=1 , i##_len=(int)(n);i<=i##_len;i++)
#define rrep(i,n) for(int i=((int)(n)-1);i>=0;i--)
#define rreps(i,n) for(int i=((int)(n));i>0;i--)
#define repi(i,x) for(auto i=(x).begin(),i##_fin=(x).end();i!=i##_fin;i++)
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define solve(a) ((a)?"Yes":"No")
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef pair<int , int> Pi;
typedef vector<Pi> VPi;
typedef vector<long long> V;
typedef vector<V> VV;
typedef pair<long long , long long> P;
typedef vector<P> VP;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1;} return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1;} return 0;}
const long long INFLL = 1LL<<50;
const int INF = 1<<30;
const double PI=acos(-1);
//ワーシャルフロイゼ法(隣接行列を受け取り、それぞれの最短を受け取る、size:10^2-)
//ダイクストラ法:スタートから任意の地点での最短距離を求める
//計算量:(頂点+辺)log(頂点) 
//始点,終点,隣接リスト(pathlist[edge.A]=(edgeB,legth))-->距離(notfound:INFLL);
vector<long long> Dikstra(int start,vector<vector<pair<int,long long>>>&pathlist){
	int edge=pathlist.size();
	pair<long long, int> cerching;
	priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> q; //start to distance,[ditance ,islandNo.]
	vector<long long> D(edge,INFLL); //distance (ans)
	vector<bool>had(edge,false);
	D[start] = 0;
	q.emplace(0LL, start);

	while (!q.empty()){
		cerching = q.top();
		q.pop();
		if (had[cerching.second] == false){
			had[cerching.second] = true;


			for (auto i = pathlist[cerching.second].begin(); i != pathlist[cerching.second].end(); i++){
				if (had[i->first] == false){
					chmin(D[i->first], (cerching.first) + (i->second));
					q.emplace(D[i->first], i->first);
				}
			}
		}
	}


return D;
}
//https://onlinejudge.u-aizu.ac.jp/challenges/search/volumes/1166
int main(){
	int w,h;
	ll ans=INFLL;
	int bef;
	pair<int,int>po=mp(0,0);
	vector<vector<pair<int, long long>>> path;
	while (1)
	{
		cin >> w >> h;
		if (h == w and h == 0)
		{
			return 0;
		}
		path.clear();
		path.resize(h*w);
		for (int i = 0; i < (2 * h) -1; i++)
		{
			for (int j = 0; j < w+((i % 2==0) ? -1 : 0); j++){
				cin >> bef;
				//
				/*
				if (i % 2 == 0)
				{
					clog << (i / 2) * w + (j) << " to " << (i / 2) * w +( j + 1) << " -- " << bef << endl;
				}
				else
				{
					clog << (i / 2) * w + (j) << " to " << ((i + 1) / 2) * w + (j)  << " -- " << bef << endl;
				}
				*/
				//
				if(!bef){
					if(i%2==0){
						path[(i / 2) * w + (j)].emplace_back((i / 2) * w + (j + 1), 1LL);
						path[(i / 2) * w + (j + 1)].emplace_back((i / 2) * w + (j), 1LL);
					}else{
						path[(i / 2) * w + (j)].emplace_back(((i + 1) / 2) * w + (j), 1LL);
						path[((i + 1) / 2) * w + (j)].emplace_back((i / 2) * w + (j), 1LL);
					}
					
				}
			}
		}
		//
		/*
		rep(i,h*w){
			repi(itr,path[i]){
				clog<<(itr->F)<<" ";
			}
			clog<<endl;
		}
		*/
		//
		ans=Dikstra(0,path)[h*w-1];
		if(ans==INFLL){
			cout<<0<<endl;
		}else{
		cout << ans+1 << endl;
	}
	}
}