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++: // clang-format off
#include <bits/stdc++.h>
using namespace std;
#define overload4(_1, _2, _3, _4, name, ...) name
#define rep4(i, a, b, c) for (int i = int(a), i##__b = int(b), i##__c = int(c); i < i##__b; i += i##__c)
#define rep1(n) rep4(i, 0, n, 1)
#define rep2(i, n) rep4(i, 0, n, 1)
#define rep3(i, a, b) rep4(i, a, b, 1)
#define REP(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep3(i, a, b) for (int i = int(b) - 1, i##__a = int(a); i >= i##__a; i--)
#define rrep1(n) rrep3(i, 0, n)
#define rrep2(i, n) rrep3(i, 0, n)
#define rrep4(i, a, b, c) for (int i = int(a + (b - a - 1) / c * c), i##__a = int(a), i##__c = int(c); i >= i##__a; i -= i##__c)
#define RREP(...) overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)
#define FOREACH(i, x) for (auto &i : x)
#define pb(x) push_back(x)
#define mp(x, y) make_pair(x, y)
#define mt make_tuple
#define print(x) cout << x << endl;
const int MOD = 1e9 + 7;
const int INF = 1e9 + 9;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
using vint = vector<int>;
using vvint = vector<vector<int>>;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using vbool = vector<bool>;
using vvbool = vector<vector<bool>>;
using vstring = vector<string>;
template <class T> using vv = vector<vector<T>>;
template <class T> bool chmax(T &a, const T &b) {if (a < b) {a = b;return 1;}return 0;}
template <class T> bool chmin(T &a, const T &b) {if (b < a) {a = b;return 1;}return 0;}

struct Point {int x, y; Point(int x, int y):x(x), y(y){}};
int dx[] = {1, 0, -1, 0}; int dy[] = {0, 1, 0, -1};
pii dvs[] = {mp(1, 0), mp(0, 1), mp(-1, 0), mp(0, -1)};
// clang-format on


int main() {
    int W, H;
    cin >> W >> H;
    for (; W != 0 || H != 0; cin >> W >> H) {
        // 座標 : 0-indexed
        // 座標(x,y)の左に壁があるとき : l[y][x]==1
        // 座標(x,y)の右に壁があるとき : l[y][x+1]==1
        vvint l(H, vint(W + 1, 1));
        vvint u(H + 1, vint(W, 1));

        REP(x, 1, W) {
            cin >> l[0][x];
        }
        REP(y, 1, H) {
            REP(x, W) {
                cin >> u[y][x];
            }
            REP(x, 1, W) {
                cin >> l[y][x];
            }
        }
        queue<pii> q;
        vvint saitan(H, vint(W, -1));
        saitan[0][0] = 1;
        int x = 0, y = 0;
        for (; !(x == W - 1 && y == H - 1); tie(x, y) = q.front(), q.pop()) {
            // 左の更新
            if (!l[y][x] && saitan[y][x - 1] == -1) {
                q.push(mp(x - 1, y));
                saitan[y][x - 1] = saitan[y][x] + 1;
            }
            // 右の更新
            if (!l[y][x + 1] && saitan[y][x + 1] == -1) {
                q.push(mp(x + 1, y));
                saitan[y][x + 1] = saitan[y][x] + 1;
            }
            // 上の更新
            if (!u[y][x] && saitan[y - 1][x] == -1) {
                q.push(mp(x, y - 1));
                saitan[y - 1][x] = saitan[y][x] + 1;
            }
            // 下の更新
            if (!u[y + 1][x] && saitan[y + 1][x] == -1) {
                q.push(mp(x, y + 1));
                saitan[y + 1][x] = saitan[y][x] + 1;
            }
            if (q.empty()) break;
        }

        if (saitan[H - 1][W - 1] == -1) {
            print(0);
        } else {
            print(saitan[H - 1][W - 1]);
        }
    }
}