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 namespace std;

#define MAX 31
#define INF (1<<30)
int W, H, d[MAX][MAX], T[MAX][MAX], Y[MAX][MAX];

void bfs(){
    queue<pair<int, int> > todo;
    todo.push(make_pair(0, 0));
    while(!todo.empty()){
        int x = todo.front().first, y = todo.front().second;
        todo.pop();
        if(!Y[x][y] && d[x - 1][y] == INF){
            d[x - 1][y] = d[x][y] + 1;
            todo.push(make_pair(x - 1, y));
        }
        if(!T[x][y] && d[x][y - 1] == INF){
            d[x][y - 1] = d[x][y] + 1;
            todo.push(make_pair(x, y - 1));
        }
        if(!Y[x + 1][y] && d[x + 1][y] == INF){
            d[x + 1][y] = d[x][y] + 1;
            todo.push(make_pair(x + 1, y));
        }
        if(!T[x][y + 1] && d[x][y + 1] == INF){
            d[x][y + 1] = d[x][y] + 1;
            todo.push(make_pair(x, y + 1));
        }
    }
    return;
}

int main(){
    while(cin >> W){
        if(W == 0) return 0;
        cin >> H;
        for(int i = 0; i < H; i++) for(int j = 0; j < W; j++) d[i][j] = INF;
        d[0][0] = 1;
        for(int i = 0; i < H; i++) T[i][0] = T[i][W] = 1;
        for(int i = 0; i < W; i++) Y[0][i] = Y[H][i] = 1;
        for(int i = 0; i < H; i++){
            if(i) for(int j = 0; j < W; j++) cin >> Y[i][j];
            for(int j = 1; j < W; j++) cin >> T[i][j];
        } 
        bfs();
        cout << (d[H - 1][W - 1] == INF ? 0 : d[H - 1][W - 1]) << endl;
    }
}

C++: #pragma GCC optimize ("O3")

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include <prettyprint.hpp>
#define debug(...)  cerr << "[" << #__VA_ARGS__ << "]: ", d_err(__VA_ARGS__);
#else
#define debug(...) 83;
#endif

void d_err() {
    cerr << endl;
}

template <typename H, typename... T>
void d_err(H h, T... t) {
    cerr << h << " ";
    d_err(t...);
}

template <typename T>
void print(T x) {
    cout << x << "\n";
}

#define ALL(x) (x).begin(), (x).end()
#define FOR(i, m, n) for (int i = (m); i < (n); ++i)
#define REVFOR(i, m, n) for (int i = (n - 1); i >= (m); --i)
#define REP(i, n) FOR(i, 0, n)
#define REVREP(i, n) REVFOR(i, 0, n)
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define bcnt __builtin_popcountll

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<ll,ll> Pll;
typedef pair<int,int> Pin;

ll INF = 1e16;
int inf = 1e9;
ll MOD = 1e9+7;


int main() {
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    vi dx = {0, 1, 0, -1}, dy = {1, 0, -1, 0};

    while(true) {
        int w, h; cin >> w >> h;

        if (w == 0 && h == 0) break;
        vector<vector<bool>> maze(h * w, vector<bool>(h * w, true));

        REP(i, 2 * h - 1) {
            if (i & 1) {
                // horizontal
                int hi = i / 2;
                REP(j, w) {
                    int b;
                    cin >> b;
                    if (b == 0) continue;
                    maze[hi * w + j][(hi + 1) * w + j] = false;
                    maze[(hi + 1) * w + j][hi * w + j] = false;
                }
            } else {
                // vertical
                int hi = i / 2;
                REP(j, w - 1) {
                    int b;
                    cin >> b;
                    if (b == 0) continue;
                    maze[hi * w + j][hi * w + j + 1] = false;
                    maze[hi * w + j + 1][hi * w + j] = false;
                }
            }
        }

        auto check = [&](int x, int y) -> bool {
            return x >= 0 && x < w && y >= 0 && y < h;
        };

        queue<pair<int, Pin>> q;
        q.push({1, {0, 0}});
        vector<vector<bool>> visit(h, vector<bool>(w, false));
        visit[0][0] = true;

        int ans = 0;
        while(!q.empty()) {
            auto p = q.front(); q.pop();
            int x = p.se.fi, y = p.se.se;
            int d = p.fi;

            if (x == w - 1 && y == h - 1) {
                ans = d;
                break;
            }

            REP(i, 4) {
                int nx = x + dx[i], ny = y + dy[i];
                if (!check(nx, ny) || !maze[y * w + x][ny * w + nx]) continue;

                if (!visit[ny][nx]) {
                    visit[ny][nx] = true;
                    q.push({d + 1, {nx, ny}});
                }
            }
        }

        print(ans);
    }

}