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;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
typedef long long int ll;

#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define endl "\n"
const double EPS = 1e-7;
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
const double PI = acos(-1);
const int MOD = 1000000007;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

//-------------------------------------

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    while(1) {
        int h, w;
        cin >> w >> h;
        if(w == 0 && h == 0) {
            break;
        }
        int n = h * w + 2;
        vector<vector<int>> g(n);
        g[0].emplace_back(1);
        g[1].emplace_back(0);
        g[n - 2].emplace_back(n - 1);
        g[n - 1].emplace_back(n - 2);
        for(int i = 1; i <= h; i++) {
            for(int j = 1; j <= w - 1; j++) {
                int tmp;
                cin >> tmp;
                if(tmp == 0) {
                    g[w * (i - 1) + j].emplace_back(1 + w * (i - 1) + j);
                    g[1 + w * (i - 1) + j].emplace_back(w * (i - 1) + j);
                }
            }
            if(i == h) {
                break;
            }
            for(int j = 1; j <= w; j++) {
                int tmp;
                cin >> tmp;
                if(tmp == 0) {
                    g[w * (i - 1) + j].emplace_back(w * i + j);
                    g[w * i + j].emplace_back(w * (i - 1) + j);
                }
            }
        }
        vector<int> d(n, INF);
        d[0] = 0;
        queue<int> que;
        que.push(0);
        while(que.size()) {
            int v = que.front();
            que.pop();
            if(d[v] == INF) {
                continue;
            }
            for(auto u : g[v]) {
                if(d[u] == INF) {
                    d[u] = d[v] + 1;
                    que.push(u);
                }
            }
        }
        cout << (d[n - 1] == INF ? 0 : d[n - 1] - 1) << endl;
    }
}

C++: #include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

//#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
const double PI = acos(-1);
const double EPS = 1e-9;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }


int dp[40][40][40][40];
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int w, h;
	while (cin >> w >> h, w&&h) {
		memset(dp, 0x3f, sizeof(dp));
		rep(i, 0, h)rep(j, 0, w)dp[i][j][i][j] = 0;
		rep(i, 0, 2 * h - 1) {
			if (i % 2 == 0) {
				rep(j, 0, w - 1) {
					int x; cin >> x;
					// i/2 j,j+1
					dp[i / 2][j][i / 2][j + 1] = (x ? INF : 1);
					dp[i / 2][j + 1][i / 2][j] = (x ? INF : 1);
				}
			}
			else {
				rep(j, 0, w) {
					int x; cin >> x;
					// i/2 i/2+1 j
					dp[i / 2][j][i / 2 + 1][j] = (x ? INF : 1);
					dp[i / 2 + 1][j][i / 2][j] = (x ? INF : 1);
				}
			}
		}
		//rep(a, 0, h)rep(b, 0, w)rep(i, 0, h)rep(j, 0, w)rep(x, 0, h)rep(y, 0, w) {
		//	chmin(dp[i][j][x][y], dp[i][j][a][b] + dp[a][b][x][y]);
		//}
		queue<pair<int, int>>q;
		q.push(make_pair(0, 0));
		int dx[] = { 1,0,-1,0 }, dy[] = { 0,1,0,-1 };
		auto within = [&](int x, int y) {return 0 <= x&&x < h && 0 <= y&&y < w; };
		vector<vector<int>>d(h, vector<int>(w, -1));
		while (!q.empty()) {
			auto u = q.front(); q.pop();
			rep(i, 0, 4) {
				int x = u.first+dx[i], y = u.second+dy[i];
				if (within(x, y)&&dp[u.first][u.second][x][y]==1&&d[x][y]==-1) {
					q.push(make_pair(x, y));
					d[x][y] = d[u.first][u.second] + 1;
				}
			}
		}

		int ans = d[h - 1][w - 1];
		cout << (ans == -1 ? 0 : ans + 1+1) << endl;
	}
	return 0;
}