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 <algorithm>
#include <vector>
#include <cfloat>
#include <string>
#include <cmath>
#include <set>
#include <cstdlib>
#include <map>
#include <ctime>
#include <iomanip>
#include <functional>
#include <deque>
#include <iostream>
#include <cstring>
#include <queue>
#include <cstdio>
#include <stack>
#include <climits>
#include <sys/time.h>
#include <cctype>

using namespace std;

typedef long long ll;

bool kabe[31][31][31][31];
int dx[] = {0, 0, -1, 1};
int dy[] = {-1, 1, 0, 0};
bool vis[31][31];
int memo[31][31];
int w, h;
void solve(int x, int y) {
  for (int i = 0; i < 4; i++) {
    int nx = x+dx[i];
    int ny = y+dy[i];

    if (nx < 0 || ny < 0 || nx >= w || ny >= h ||
	(memo[nx][ny] != -1 && memo[x][y]+1 >= memo[nx][ny]) ||
	vis[nx][ny] ||
	kabe[x][y][nx][ny]) {
      continue;
    }

    vis[nx][ny] = true;
    memo[nx][ny] = memo[x][y]+1;
    solve(nx, ny);
    vis[nx][ny] = false;
  }
}

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

    memset(kabe, false, sizeof(kabe));
    memset(vis, false, sizeof(vis));
    for (int i = 0; i < 2*h-1; i++) {
      int l = i%2 ? w : w-1;
      for (int j = 0; j < l; j++) {
	int t;
	cin >> t;
	if (t == 1) {
	  if (i%2) {
	    // std::cout << "(" << j << "," << i/2 << ")と(" << j << "," << i/2+1 << ")に壁がある。" << std::endl;
	    kabe[j][i/2][j][i/2+1] = true;
	    kabe[j][i/2+1][j][i/2] = true;
	  }else {
	    // std::cout << "(" << j << "," << i/2 << ")と(" << j+1 << "," << i/2 << ")に壁がある。" << std::endl;
	    kabe[j][i/2][j+1][i/2] = true;
	    kabe[j+1][i/2][j][i/2] = true;
	  }
	}
      }
    }
    memset(memo, -1, sizeof(memo));

    vis[0][0] = true;
    solve(0, 0);

    if (memo[w-1][h-1] == -1) {
      std::cout << 0 << std::endl;
    }else {
      std::cout << memo[w-1][h-1]+2 << std::endl;
    }
  }
}

C++: #include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
#include <cctype>

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; }

const long long MAX = 5100000;
const long long INF = 1LL << 60;
const long long mod = 1000000007LL;
//const long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;




int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/
	while (1) {
		ll W, H; scanf("%lld %lld", &W, &H);
		if (W == 0 && H == 0) break;
		vector<vector<ll>> yo(H, vector<ll>(W - 1));
		vector<vector<ll>> ta(H, vector<ll>(W));
		for (ll i = 0; i < H; i++) {
			for (ll j = 0; j < W - 1; j++) scanf("%lld", &yo[i][j]);
			if (i != H - 1) for (ll j = 0; j < W; j++) scanf("%lld", &ta[i][j]);
		}
		queue<pair<ll, ll>> q;
		q.emplace(0, 0);
		vector<vector<ll>> d(H, vector<ll>(W, -1));
		while (!q.empty()) {
			ll h, w; tie(h, w) = q.front();
			q.pop();
			if (h > 0 && ta[h-1][w] == 0 && d[h-1][w] == -1) {
				d[h - 1][w] = d[h][w] + 1;
				q.emplace(h - 1, w);
			}
			if (h < H - 1 && ta[h][w] == 0 && d[h + 1][w] == -1) {
				d[h + 1][w] = d[h][w] + 1;
				q.emplace(h + 1, w);
			}
			if (w > 0 && yo[h][w - 1] == 0 && d[h][w - 1] == -1) {
				d[h][w - 1] = d[h][w] + 1;
				q.emplace(h, w - 1);
			}
			if (w < W - 1 && yo[h][w] == 0 && d[h][w + 1] == -1) {
				d[h][w + 1] = d[h][w] + 1;
				q.emplace(h, w + 1);
			}
		}
		ll res = d[H - 1][W - 1];
		if (res == -1) res = -2;
		printf("%lld\n", res + 2);
	}
	return 0;
}