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 <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>

using namespace std;

inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str();}

typedef vector<int> vi;
typedef vector<vi>  vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EACH(t,i,c) for(t::iretator i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

const double EPS = 1e-10;

#define OPEN 0
#define UP_WALL 1
#define LEFT_WALL 2
#define DOWN_WALL 4
#define RIGHT_WALL 8

int main() {
	int w, h;

	while(cin >> w >> h, w) {
		vvi field(h+2, vi(w+2, OPEN));
		vvi cost(h+2, vi(w+2, 1000000));
		vvi visited(h+2, vi(w+2, 0));

		FOR(i, 1, h+1) {
			FOR(j, 1, h+1) {
				field[i][j] = OPEN;
				cost[i][j] = 1000000;
			}
		}

		FOR(i, 1, w+1) {
			field[1][i] += UP_WALL;
			field[h][i] += DOWN_WALL;
		}
		FOR(i, 1, h+1) {
			field[i][1] += LEFT_WALL;
			field[i][w] += RIGHT_WALL;
		}
		
		FOR(i, 1, h*2) {
			if(i%2) {
				FOR(j, 1, w) {
					int tmp;
					cin >> tmp;
					if(tmp) {
						field[i/2+1][j] += RIGHT_WALL;
						field[i/2+1][j+1] += LEFT_WALL;
					}

				}
			} else {
				FOR(j, 1, w+1) {
					int tmp;
					cin >> tmp;
					if(tmp) {
						field[i/2][j] += DOWN_WALL;
						field[i/2+1][j] += UP_WALL;
					}
				}
			}
		}

		//make cost map
		queue<pii> route;
		route.push(make_pair(1, 1));
		cost[1][1] = 1;

		while(!route.empty()) {
			pii zahyou = route.front();
			route.pop();

			int x = zahyou.first;
			int y = zahyou.second;

			if((field[y][x]&UP_WALL) == 0) {
				if(cost[y-1][x] > cost[y][x]) {
					cost[y-1][x] = cost[y][x]+1;
					if(visited[y-1][x] == 0) {
						route.push(make_pair(x, y-1));
						visited[y-1][x] = 1;
					}
				}
			}
			if((field[y][x]&LEFT_WALL) == 0) {
				if(cost[y][x-1] > cost[y][x]) {
					cost[y][x-1] = cost[y][x]+1;
					if(visited[y][x-1] == 0) {
						route.push(make_pair(x-1, y));
						visited[y][x-1] = 1;
					}
				}
			}
			if((field[y][x]&DOWN_WALL) == 0) {
				if(cost[y+1][x] > cost[y][x]) {
					cost[y+1][x] = cost[y][x]+1;
					if(visited[y+1][x] == 0) {
						route.push(make_pair(x, y+1));
						visited[y+1][x] = 1;
					}
				}
			}
			if((field[y][x]&RIGHT_WALL) == 0) {
				if(cost[y][x+1] > cost[y][x]) {
					cost[y][x+1] = cost[y][x]+1;
					if(visited[y][x+1] == 0) {
						route.push(make_pair(x+1, y));
						visited[y][x+1] = 1;
					}
				}
			}

			if(x == w && y == h) {
				break;
			}
		}

		if(cost[h][w] != 1000000) {
			cout << cost[h][w] << endl;
		} else {
			cout << -1 << endl;
		}
	}

	return 0;
}