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 <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <vector>
#include <string>
#include <queue>
#include <deque>
#include <list>
#include <stack>
#include <set>
#include <map>
#include <algorithm>

#define int long long
#define MOD7 1000000007
#define MOD9 1000000009

#define rep(i, n) for (int i = 0; i < (n); i++)
#define all(a) (a).begin(), (a).end()

using namespace std;

int nextInt() {int a; cin >> a; return a;}
char nextChar() {char a; cin >> a; return a;}
double nextDouble() {double a; cin >> a; return a;}
string nextString() {string a; cin >> a; return a;}

void inputVector(vector<int> &v, int &n) {rep(i,n){v.push_back(nextInt());}}
void inputVector(vector<double> &v, int &n) {rep(i,n){v.push_back(nextDouble());}}
void inputVector(vector<string> &v, int &n) {rep(i,n){v.push_back(nextString());}}

class Graph {
private:
	// ?????\?????¨??????????????±
	struct QInfo {
		int nodeNum;    // ???????????????
		long long dist;	    // ?????¢

		// ?????????????????????
		QInfo(int argNum, long long argDist) {
			nodeNum = argNum;
			dist = argDist;
		}
		// ??????????????????????????????
		bool operator<(const QInfo& a) const {
			return dist > a.dist;
		}
	};

public:
	// ??¨??????????????±
	struct Edge {
		int next;	    	// ????§????????????????
		long long weight;	// ??¨???????????????

		// ?????????????????????
		Edge() {
			next = -1;
			weight = 0;
		}
		Edge(int argNext, int argWeight) {
			next = argNext;
			weight = argWeight;
		}
	};
	// ?????????????????±
	struct Node {
		long long dist;	    // ????????????????????¨?????¢
		vector<Edge> edge;  // ??\?¶?????????¨???????????±
	};

	// ??????????????????
	vector<Node> node;

	/*
	/  ?????????????????????
	/  - ?????°??§????????????????????°????????????????????????
	*/
	Graph(int num) {
		for (int i = 0; i < num; i++) {
			node.push_back(Node());
		}
	}

	/*
	/  addNode
	/  - ??????????????????
	/   num : ?????????????????°
	*/
	void addNode(int num) {
		for (int i = 0; i < num; i++) {
			node.push_back(Node());
		}
	}

	/*
	/  makeEdge
	/  - ??¨???????????????
	/   prevNode : ??\?¶??????????????????????
	/   nextNode : ??\?¶??????????????????????
	/   weight   : ??¨???????????????
	/   flagBidirect : ??????????????¨??????????????????
	*/
	void makeEdge(int prevNode, int nextNode, long long weight, bool flagBidirect) {
		node[prevNode].edge.push_back(Edge(nextNode, weight));
		if (flagBidirect) {
			node[nextNode].edge.push_back(Edge(prevNode, weight));
		}
	}

	/*
	/  deleteEdge
	/  - ??¨?????????????????????
	/   prevNode : ??\?¶??????????????????????
	/   nextNode : ??\?¶??????????????????????
	/   flagBidirect : ????????????????????¨????????????
	/   ????????? : ?????????????????????????????????
	*/
	bool deleteEdge(int prevNode, int nextNode, bool flagBidirect) {
		bool flagDelete = false;
		vector<Edge>::iterator it;
		// prevNode -> nextNode ?????????
		for (it = node[prevNode].edge.begin(); it != node[prevNode].edge.end(); it++) {
			if ((*it).next == nextNode) {
				node[prevNode].edge.erase(it);
				it--;
				flagDelete = true;
			}
		}

		if (!flagBidirect) return flagDelete;

		// nextNode -> prevNode ?????????
		for (it = node[nextNode].edge.begin(); it != node[nextNode].edge.end(); it++) {
			if ((*it).next == prevNode) {
				node[nextNode].edge.erase(it);
				it--;
				flagDelete = true;
			}
		}

		return flagDelete;
	}

	/*
	/  changeWeight
	/  - ??¨???????????????????????´??????
	/   prevNode : ????§??????????????????????
	/   nextNode : ????§??????????????????????
	/   weight   : ?????´????????????
	/   flagBidirect : ????????????????????¨????????????
	/   ????????? : ?????´???????????????????????????
	*/
	bool changeWeight(int prevNode, int nextNode, long long weight, bool flagBidirect) {
		bool flagChange = false;
		vector<Edge>::iterator it;
		for (it = node[prevNode].edge.begin(); it != node[prevNode].edge.end(); it++) {
			if ((*it).next == nextNode) {
				(*it).weight = weight;
				flagChange = true;
			}
		}

		if (!flagBidirect) return flagChange;

		for (it = node[nextNode].edge.begin(); it != node[nextNode].edge.end(); it++) {
			if ((*it).next == prevNode) {
				(*it).weight = weight;
				flagChange = true;
			}
		}

		return flagChange;
	}

	/*
	/  dijkstra
	/  - ???????????????????????§????????????????????¢????±???????
	/  - startNode??????????????¢??????node???dist???????´??????????
	/  - ?¨???????O((E + V)logV)
	/   startNode : ???????????????????????????
	/   endNode   : ??´????????????????????????
	/   ????????? : 2??????????????¢
	*/
	int dijkstra(int startNode, int endNode) {

		// ?????¢?????????
		for (int i = 0; i < node.size(); i++) {
			node[i].dist = LLONG_MAX;
		}
		node[startNode].dist = 0;

		priority_queue<QInfo> q;
		set<int> inq;
		q.push(QInfo(startNode, 0));
		inq.insert(startNode);
		while (!q.empty()) {
			QInfo now = q.top(); q.pop();
			Node nowNode = node[now.nodeNum];
			inq.erase(now.nodeNum);

			for (vector<Edge>::iterator it = nowNode.edge.begin(); it != nowNode.edge.end(); it++) {
				int nextNode = (*it).next;
				if (nowNode.dist + (*it).weight < node[nextNode].dist) {
					// ?????¢?????´??°
					node[nextNode].dist = nowNode.dist + (*it).weight;

					// ?????\????????\??£??????????????°push
					if (inq.find(nextNode) == inq.end()) {
						q.push(QInfo(nextNode, node[nextNode].dist));
						inq.insert(startNode);
					}
				}
			}
		}

		return node[endNode].dist;
	}

	/*
	/  bellmanFord
	/  - ?????????????????????????????§????????????????????¢????±???????
	/  - startNode??????????????¢??????node???dist???????´??????????
	/  - ???????????????????????°???LLONG_MIN???????´???????
	/  - ?¨???????O(VE)
	/   startNode : ???????????????????????????
	/   endNode   : ??´????????????????????????
	/   ????????? : 2??????????????¢
	*/
	int bellmanFord(int startNode, int endNode) {
		// ?????¢?????????
		for (int i = 0; i < node.size(); i++) {
			node[i].dist = LLONG_MAX;
		}
		node[startNode].dist = 0;

		// ?????????????????????
		for (int i = 0; i < node.size(); i++) {
			for (auto nd : node) {
				if (nd.dist == LLONG_MAX) continue;

				for (auto ed : nd.edge) {
					if (node[ed.next].dist > nd.dist + ed.weight) {
						node[ed.next].dist = nd.dist + ed.weight;
					}
				}
			}
		}

		// ????????????????????§??????
		for (auto nd : node) {
			if (nd.dist == LLONG_MAX) continue;

			for (auto ed : nd.edge) {
				if (node[ed.next].dist > nd.dist + ed.weight) {
					return LLONG_MIN;
				}
			}
		}

		return node[endNode].dist;
	}
};

signed main() {
	while (true) {
		int w, h;
		cin >> w >> h;
		
		if (w == 0) break;

		auto g = Graph(w * h);
		for (int y = 0; y < h - 1; y++) {
			for (int x = 0; x < w; x++) {
				g.makeEdge(y * w + x, (y + 1) * w + x, 1, true);
			}
		}
		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w - 1; x++) {
				g.makeEdge(y * w + x, y * w + x + 1, 1, true);
			}
		}

		int cnt = 0;
		rep(i, h * 2 - 1) {
			int y = i / 2;
			if (i % 2 == 0) {
				rep(x, w - 1) {
					bool input;
					cin >> input;

					if (input) {
						g.deleteEdge(y * w + x, y * w + x + 1, true);
					}
				}
			} else {
				rep(x, w) {
					bool input;
					cin >> input;

					if (input) {
						g.deleteEdge(y * w + x, (y + 1) * w + x, true);
					}
				}
			}
		}

		int dist = g.dijkstra(0, h * w - 1);
		cout << (dist == LLONG_MAX ? 0 : dist + 1) << endl;
	}

    return 0;
}