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>
//#define int long long

using namespace std;
using LL = long long;
using P = pair<int, int>;
using Tapris = tuple<int, int, int>;

#define REP(i, n) for(LL i = 0; i < n; ++i)
#define FOR(i, a, n) for(LL i = a; i < n; ++i)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()

const int INF = (int)1e9;
const LL INFL = (LL)1e15;
const int MOD = 1e9 + 7;

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

/*************** using variables ***************/
int w, h;
int dp[905][905];
/**********************************************/
struct Edge {
    int cost, to;
    Edge(int t, int c) {
        cost = c;
        to = t;
    }
    bool operator<(const Edge &e) const { return cost < e.cost; }
    bool operator>(const Edge &e) const { return cost > e.cost; }
};

template <typename T>
class Dijkstra {
    private:
        bool isDir = false;  // 無向グラフ: false, 有向グラフ: true
        T INF = numeric_limits<T>::max();
        int V;                     // 頂点数
        vector<vector<Edge>> adj;  // adj[始点][動的配列で始点から伸びる枝]
        vector<int> prever;

    public:
        Dijkstra(int n, bool dir);
        vector<T> cost;
        void AddEdge(int f, int t, int c);
        bool HasPath(int t);                 // tに至るパスはあるか
        vector<int> getShortestPath(int t);  // tへの最短路
        void Run(int f);
};

    template <typename T>
Dijkstra<T>::Dijkstra(int n, bool dir)
    : isDir(dir),
    V(n + 1),
    adj(vector<vector<Edge>>(V)),
    prever(vector<int>(V, -1)),
    cost(vector<T>(V)) {
        fill(cost.begin(), cost.end(), INF);
    }

template <typename T>
void Dijkstra<T>::AddEdge(int f, int t, int c) {
    adj[f].push_back(Edge(t, c));
    if (!isDir) adj[t].push_back(Edge(f, c));
}

template <typename T>
bool Dijkstra<T>::HasPath(int t) {
    return cost[t] != INF;
}

template <typename T>
vector<int> Dijkstra<T>::getShortestPath(int t) {
    vector<int> path;
    for (; t != -1; t = prever[t]) path.push_back(t);

    reverse(path.begin(), path.end());
    return path;
}

template <typename T>
void Dijkstra<T>::Run(int firstNode) {
    priority_queue<Edge, vector<Edge>, greater<Edge>> pq;

    cost[firstNode] = 0;
    pq.push(Edge(firstNode, 0LL));

    while (!pq.empty()) {
        Edge currentEdge = pq.top();
        pq.pop();

        if (cost[currentEdge.to] < currentEdge.cost) continue;

        for (Edge tmp : adj[currentEdge.to]) {
            T sumCost = currentEdge.cost + tmp.cost;
            if (cost[tmp.to] > sumCost) {
                cost[tmp.to] = sumCost;
                prever[tmp.to] = currentEdge.to;
                pq.push(Edge(tmp.to, cost[tmp.to]));
            }
        }
    }
}
signed main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    while(cin >> w >> h, w != 0 || h != 0){
        Dijkstra<int> dj(w*h, false);
        /*
        REP(i, w*h) REP(j, w*h) dp[i][j] = (i == j ? 0 : INF);
        REP(i, h){
            REP(j, w-1){
                int x; cin >> x;
                if(x == 0){
                    dp[i*w+j][i*w+j+1] = 1;
                    dp[i*w+j+1][i*w+j] = 1;
                }
            }
            if(i < h-1){ 
                REP(j, w){
                    int x; cin >> x;
                    if(x == 0){
                        dp[i*w+j][(i+1)*w+j] = 1;
                        dp[(i+1)*w+j][i*w+j] = 1;
                    }
                }
            }
        }
        
        REP(k, w*h) REP(i, w*h) REP(j, w*h) dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j]);

        cout << (dp[0][w*h-1] == INF ? 0 : dp[0][w*h-1]+1) << endl;
        */
    
        REP(i, h){
            REP(j, w-1){
                int x; cin >> x;
                if(x == 0){
                    dj.AddEdge(i*w+j, i*w+j+1, 1);
                }
            }
            if(i < h-1){ 
                REP(j, w){
                    int x; cin >> x;
                    if(x == 0){
                        dj.AddEdge(i*w+j, (i+1)*w+j, 1);
                    }
                }
            }
        }
        dj.Run(0);
        if(dj.HasPath(w*h-1)) cout << dj.cost[w*h-1] + 1 << endl;
        else cout << 0 << endl;
    }
}