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;
using ll = long long;
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define SORT(c) sort((c).begin(),(c).end())
#define MEMSET(v, h) memset((v), h, sizeof(v))
#define sqr(x) ((x) * (x))
#define bit(n) (1LL<<(n))
#define pcnt(x) __builtin_popcountll(x)
#define PB push_back
#define MP make_pair
#define endl "\n"
using Edge = pair<int,int>;
using Graph = vector<vector<Edge>>;
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; }
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
// ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

  const int dx[4] = {1, 0, -1, 0};
  const int dy[4] = {0, 1, 0, -1};
  const int INF = 1001001001;


int main() {
  while(1){
    queue<pair<int,int>> que;
    int w,h; cin >> w >> h;
    if(w==0 && h==0) break;
    int length[h][w];
    FOR(i,0,h-1){
      FOR(j,0,w-1){
        length[i][j] = INF;
      }
    }
    bool ver[h][w];
    bool par[h][w];
    FOR(i,1,2*h-1){
      if(i%2==1){
        FOR(j,0,w-2){
          bool c; cin >> c;
          ver[(i-1)/2][j] = c;
        }
      } else {
        FOR(j,0,w-1){
          bool c; cin >> c;
          par[(i-2)/2][j] = c;
        }
      }
    }
    que.push(MP(0,0));
    length[0][0] = 1;
    while(!que.empty()){
      int ny,nx;
      Edge p = que.front();
      que.pop();
      FOR(i,0,3){
        ny = p.first + dy[i];
        nx = p.second + dx[i];
        if(ny<0 || nx<0 || ny>=h || nx>=w || length[ny][nx]!=INF) continue;
        if(dy[i]==1 && par[p.first][p.second]) continue;
        if(dy[i]==-1 && par[p.first-1][p.second]) continue;
        if(dx[i]==1 && ver[p.first][p.second]) continue;
        if(dx[i]==-1 && ver[p.first][p.second-1]) continue;

        que.push(MP(ny,nx));
        length[ny][nx] = length[p.first][p.second] + 1;
      }
    }
    if(length[h-1][w-1]==INF) cout << 0 << endl;
    else cout << length[h-1][w-1] << endl;
  }

}

C++: #include <iostream>
#include <queue>
#include <utility>
#include <algorithm>
#define REP(i,n) for(int i=0;i<(n);i++)
using namespace std;

typedef pair<int, int> pxy;

typedef struct{
  bool u, d, l, r;
}Wall;

int w, h;
Wall map[50][50];
int d[50][50];

bool bfs(int sx, int sy)
{
  queue<pxy> q;
  q.push(pxy(sx, sy));
  while(!q.empty()){
    int x, y;
    x = q.front().first;
    y = q.front().second;
    q.pop();
    if(x == h - 1 && y == w - 1) return true;
    if(!map[x][y].u){
      //if(d[x-1][y] == -1)
        d[x-1][y] = d[x][y] + 1;
      q.push(pxy(x-1,y));
    }
    if(!map[x][y].d){
      //if(d[x+1][y] == -1)
        d[x+1][y] = d[x][y] + 1;
      q.push(pxy(x+1,y));
    }
    if(!map[x][y].l){
      //if(d[x][y-1] == -1)
        d[x][y-1] = d[x][y] + 1;
      q.push(pxy(x,y-1));
    }
    if(!map[x][y].r){
      //if(d[x][y+1] == -1)
        d[x][y+1] = d[x][y] + 1;
      q.push(pxy(x,y+1));
    }
    map[x][y].u = map[x][y].d = map[x][y].l = map[x][y].r = true;
    if(x >= 1)
      map[x-1][y].d = true;
    if(y >= 1)
      map[x][y-1].r = true;
    map[x+1][y].u = map[x][y+1].l = true;
  }
  return false;
}

int main()
{
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    fill(&d[0][0], &d[50][0], -1);
    d[0][0] = 1;
    REP(i,50){
      REP(j,50){
        map[i][j].u = map[i][j].d = map[i][j].l = map[i][j].r = false;
      }
    }
    REP(i,2*h-1){
      int x;
      if(i & 1){
        REP(j,w){
          cin >> x;
          if(x){
            map[i/2][j].d = map[i/2][j+1].u = true;
          }
        }
      }else{
        REP(j,w-1){
          cin >> x;
          if(x){
            map[i/2][j].r = map[i/2][j+1].l = true;
          }
        }
      }
    }
    REP(i,h)
      map[i][0].l = map[i][w-1].r = true;
    REP(i,w)
      map[0][i].u = map[h-1][i].d = true;
    if(bfs(0, 0))
      cout << d[h-1][w-1] << endl;
    else
      cout << "0" << endl;
  }
}