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 iota(i,n,b,s) for(int i=int(b);i!=int((b)+(s)*(n));i+=(s))
#define range(i,n,m) iota(i,(((n)>(m))?((n)-(m)+1):((m)-(n)+1)),(n),((n)>(m)?-1:1))
#define rep(i,n) iota(i,(n),0,1)

#define INF (1e9)
#define EPS (1e-9)
#define cons(a,b) (make_pair(a,b))
#define car(a) (a.first)
#define cdr(a) (a.second)
#define cadr(a) (car(cdr(a)))
#define cddr(a) (cdr(cdr(a)))
#define all(a) a.begin(), a.end()
#define trace(var) cerr<<">>> "<<#var<<" = "<<var<<endl;

typedef long long Integer;
typedef double Real;

template<class S, class T>
ostream& operator<<(ostream& os, pair<S,T> p) {
  os << '(' << car(p) << ", " << cdr(p) << ')';
  return os;
}

template<class T>
ostream& operator<<(ostream& os, vector<T> v) {
  os << v[0];
  for (int i=1, len=v.size(); i<len; ++i) os << ' ' << v[i];
  return os;
}

int f[100][100];
int w, h;
int gx, gy;

int solve() {

  int memo[h+2][w+2];
  rep (i, h + 2) {
    rep (j, w + 2) {
      memo[i][j] = 0;
    }
  }

  queue<pair<int, pair<int, int>>> q;
  q.push(cons(1, cons(0, 0)));

  while (!q.empty())
  {
    int d = car(q.front());
    int x = cadr(q.front());
    int y = cddr(q.front());
    q.pop();

    assert(x % 2 == 0);
    assert(y % 2 == 0);

    if (memo[x/2][y/2]) continue;
    memo[x/2][y/2] = 1;

    //cerr << cons(x, y) << endl;
    if (x == gx && y == gy) return d;

    if (x > 0 && f[x-1][y] == 0)
      q.push(cons(d + 1, cons(x - 2, y)));
    if (y > 0 && f[x][y-1] == 0)
      q.push(cons(d + 1, cons(x, y - 2)));
    if (x < gx && f[x+1][y] == 0)
      q.push(cons(d + 1, cons(x + 2, y)));
    if (y < gy && f[x][y+1] == 0)
      q.push(cons(d + 1, cons(x, y + 2)));
  }
  return 0;
}

int main() {

more:;

  cin >> w >> h;

  if (!w && !h) return 0;

  gx = h + h - 2;
  gy = w + w - 2;

  rep (i, h + h - 1) {
    rep (j, w + w - 1) {
      int d = 0;
      if ((i + j) % 2) {
        cin >> d;
      }
      f[i][j] = d;
    }
  }

  cout << solve() << endl;

  goto more;
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);i++)
using namespace std;
typedef pair <int,int> pii;
#define FST first
#define SEC second
#define WMAX 60
#define HMAX 60

int dd[5]={0,1,0,-1,0};
int w,h;

/*
void print(int map[WMAX][HMAX]){
  putchar('\n');
  rep(i,h){
    rep(j,w){
      printf("%d",map[j][i]);
    }
    putchar('\n');
  }
}
*/
int dfs_aux(int map[WMAX][HMAX],int sx,int sy,int *min,int count){
  if(count<*min)
    rep(i,4){
      if(count>=*min)
	break;
      int nx=sx+dd[i],ny=sy+dd[i+1];
      if(nx<0 || w<=nx || ny<0 || h<=ny || map[nx][ny])
	continue;

      if(nx==w-1 && ny==h-1 && count<*min){
	*min=count;
	continue;
      }
    
      map[sx][sy]=1;
      dfs_aux(map,nx,ny,min,count+1);
      if(count<*min)
	break;
      map[sx][sy]=0;
    }
}

bool goal(int map[WMAX][HMAX]){
  stack <pii> s;
  s.push(pii(w-1,h-1));
  while(!s.empty()){
    int cx=s.top().FST, cy=s.top().SEC;
    s.pop();
    if(map[cx][cy]==0)
      map[cx][cy]=1;
    rep(r,4){
      int nx=cx+dd[r], ny=cy+dd[r+1];
      if(nx<0||w<=nx||ny<0||h<=ny||map[nx][ny])
	continue;
      s.push(pii(nx,ny));
    }
  }
  //print(map);
  if(map[0][0])
    return true;
  return false;
}

int dfs(int map[WMAX][HMAX]){
  int copy[WMAX][HMAX];
  rep(i,h){
    rep(j,w){
      copy[j][i]=map[j][i];
    }
  }
  if(!goal(copy))
    return 0;

  int min=INT_MAX;
  dfs_aux(map,0,0,&min,0);
  return (min+3)/2;
}

void init_map(int map[WMAX][HMAX]){
  rep(i,2*h-1){
    rep(j,2*w-1){
      map[j][i]=0;
    }
  }
}

int main(){
  int map[WMAX][HMAX];
  for(;;){
    scanf("%d%d",&w,&h);
    if(!(w+h)) break;
    init_map(map);
    rep(i,h){
      rep(j,w-1){
	scanf("%d",&map[2*j+1][2*i]);
	if(map[2*j+1][2*i]){
	  if(0 <= 2*i-1)
	    map[2*j+1][2*i-1] = 1;
	  if(2*i+1 < 2*h-1)
	    map[2*j+1][2*i+1] = 1;
	}
      }
      if(i==h-1)break;
      rep(j,w){
	int m;
	scanf("%d",&map[2*j][2*i+1]);
	if(map[2*j][2*i+1]){
	  if(0 <= 2*j-1)
	    map[2*j-1][2*i+1] = 1;
	  if(2*j+1 < 2*w-1)
	    map[2*j+1][2*i+1] = 1;
	}
      }
    }
    w=2*w-1;
    h=2*h-1;
    //print(map);
    cout << dfs(map) << endl;
  }
}