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 <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <functional>
#include <utility>
using namespace std;
#define MOD 1000000007
#define ADD(X,Y) ((X) = ((X) + (Y)%MOD) % MOD)
typedef long long i64; typedef vector<int> ivec; typedef vector<string> svec; typedef pair<int, int> pi;
int dd[] = { 0, 1, 0, -1, 0 };


int main()
{
	while (true)
	{
		int W, H;
		cin >> W >> H;
		if (W == 0 && H == 0)
		{
			break;
		}
		int C[100][100];
		for (int i = 0; i < 100; i++)
		{
			for (int j = 0; j < 100; j++)
			{
				C[i][j] = 0;
			}
		}
		int height = 0;
		for (int i = 0; i < 2 * H - 1; i++)
		{
			if (i % 2)
			{
				for (int j = 0; j < W; j++)
				{
					cin >> C[height * W + j][(height + 1) * W + j];
				}
				height++;
			}
			else
			{
				for (int j = 0; j < W - 1; j++)
				{
					cin >> C[height * W + j][height * W + j + 1];
				}
			}

		}

		int B[30][30];
		for (int i = 0; i < 30; i++)
		{
			for (int j = 0; j < 30; j++)
			{
				B[i][j] = MOD;
			}
		}
		B[0][0] = 1;

		queue<pi> Q;
		Q.push(pi(0, 0));
		while (!Q.empty())
		{
			int ty = Q.front().first; int tx = Q.front().second;
			if (ty == H - 1 && tx == W - 1)
			{
				break;
			}
			Q.pop();
			for (int r = 0; r < 4; r++)
			{
				int y = ty + dd[r];
				int x = tx + dd[r + 1];
				if (y < 0 || y >= H || x < 0 || x >= W)continue;
				if (C[y * W + x][ty * W + tx] || C[ty * W + tx][y * W + x])continue;
				if (B[y][x] != MOD)continue;
				B[y][x] = B[ty][tx] + 1;
				Q.push(pi(y, x));
			}
		}
		if (B[H - 1][W - 1] != MOD)
		{
			cout << B[H - 1][W - 1] << endl;
		}
		else
		{
			cout << 0 << endl;
		}
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG
const int INF_INT = 2147483647;
const long long INF_LONG = 9223372036854775807;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)


void f(int h, int w) {
  vector<vector<int>> g(h * 2 + 1, vector<int>(w * 2 + 1, -1));
  queue<pair<int, int>> que;
  vector<int> vy = {0, 1, 0, -1};
  vector<int> vx = {1, 0, -1, 0};
  for (int i=1; i<h*2; ++i) {
    if (i%2 == 1) for (int j=2; j<w*2; j+=2) cin >> g[i][j];
    else for (int j=1; j<w*2+1; j+=2) cin >> g[i][j];
  }
  g[1][1] = 1;

  rep (i, 4) if (g[1+vy[i]][1+vx[i]] == 0) {
    que.push(make_pair(1+vy[i]*2, 1+vx[i]*2));
    g[1+vy[i]*2][1+vx[i]*2] = 2;
  }
  while (!que.empty()) {
    int y, x;
    tie(y, x) = que.front();  que.pop();

    rep (i, 4) if (g[y+vy[i]][x+vx[i]] == 0) {
      if (y+vy[i]*2 == h*2-1 && x+vx[i]*2 == w*2-1) {
        cout << g[y][x] + 1 << endl;
        return;
      }

      if (g[y+vy[i]*2][x+vx[i]*2] == -1) {
        que.push(make_pair(y+vy[i]*2, x+vx[i]*2));
        g[y+vy[i]*2][x+vx[i]*2] = g[y][x] + 1;
      }
    }
  }

  cout << 0 << endl;
  return;
}


int main() {
  int w, h;
  cin >> w >> h;
  while (!(w == 0 && h == 0)) {
    f (h, w);
    cin >> w >> h;
  }
}

C++: #include<bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define reps(i,s,n) for(int i=(int)(s);i<(int)(n);i++)
const ll mod = ll(1e9) + 7;
const int INF = int(1e9);

int w, h;
int ww[31][31], wh[31][31];
bool m[31][31];
int solve() {
	queue <pair<pair<int, int>, int>>que;
	que.push({ {0,0},1 });
	while (que.size()) {
		int x = que.front().first.first;
		int y = que.front().first.second;
		int cnt = que.front().second;
		//cout << x << " " << y << endl;
		que.pop();
		if (x == w - 1 && y == h - 1)return cnt;
		if (x != 0) {
			if (wh[x - 1][y] != 1&&m[x-1][y]!=1) {
				que.push({ {x - 1,y},cnt + 1 });
				m[x - 1][y] = 1;
			}
		}
		if (x != w - 1) {
			if (wh[x][y] != 1 && m[x+1][y] != 1) {
				que.push({ {x + 1,y},cnt + 1 });
				m[x + 1][y] = 1;
			}
		}
		if (y != 0) {
			if (ww[x][y - 1] != 1 && m[x][y - 1] != 1) {
				que.push({ {x,y - 1},cnt + 1 });
				m[x][y - 1] = 1;
			}
		}
		if (y != h - 1) {
			if (ww[x][y] != 1 && m[x][y + 1] != 1) {
				que.push({ {x,y + 1},cnt + 1 });
				m[x][y + 1] = 1;
			}
		}
	}
	return 0;
}

int main() {
	cin.sync_with_stdio(false);
	while (1) {
		cin >> w >> h;
		if (w == 0)return 0;
		ww[31][31] = {}, wh[31][31] = {};
		int cnth = 0;
		while (cnth < h) {
			rep(i, w-1) cin >> wh[i][cnth];
			if (cnth + 1 < h) {
				rep(i, w)cin >> ww[i][cnth];
			}
			cnth++;
		}
		m[31][31] = {};
		cout << solve() << endl;

	}

	return 0;
}