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 <vector>
#include <queue>
using namespace std;

const int INF = 1 << 30;
const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, -1, 0, 1};

class Point
{
public:
  int x, y;
  Point(int _x, int _y)
    :x(_x), y(_y) {}
};

class Cell
{
public:
  bool w[4];
  Cell()
  {
    w[0] = w[1] = w[2] = w[3] = true;
  }
};

class State
{
public:
  Point p;
  int cost;
  State(Point _p, int _cost)
    :p(_p), cost(_cost) {}
  bool operator < (const State& st) const
  {
    return this->cost > st.cost;
  }
};

int main()
{
  int w, h;
  while (~scanf("%d %d", &w, &h)) {
    if (w == 0 && h == 0)
      break;

    vector<vector<Cell> > map(h, vector<Cell>(w));
    for (int i = 0; i < 2*h-1; ++i) {
      int in;
      if (i&1) {
	for (int j = 0; j < w; ++j) {
	  scanf("%d", &in);
	  map[i/2][j].w[3] = map[i/2+1][j].w[1] = in;
	}
      } else {
	for (int j = 0; j < w-1; ++j) {
	  scanf("%d", &in);
	  map[i/2][j].w[0] = map[i/2][j+1].w[2] = in;
	}
      }
    }

    int ans = 0;
    priority_queue<State> que;
    que.push(State(Point(0, 0), 1));
    vector<vector<int> > dp(h, vector<int>(w, INF));
    while (!que.empty()) {
      const State st = que.top();
      que.pop();

      if (st.p.x == w-1 && st.p.y == h-1) {
	ans = st.cost;
	break;
      }

      if (dp[st.p.y][st.p.x] < st.cost)
	continue;

      dp[st.p.y][st.p.x] = st.cost;
      for (int i = 0; i < 4; ++i) {
	if (!map[st.p.y][st.p.x].w[i]) {
	  if (dp[st.p.y+dy[i]][st.p.x+dx[i]] > st.cost+1) {
	    dp[st.p.y+dy[i]][st.p.x+dx[i]] = st.cost+1;
	    que.push(State(Point(st.p.x+dx[i], st.p.y+dy[i]), st.cost+1));
	  }
	}
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}

C++: #include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
using namespace std;
 
#define REP(i,n) for(int i=0; i<n; ++i)
#define FOR(i,a,b) for(int i=a; i<=b; ++i)
#define FORR(i,a,b) for (int i=a; i>=b; --i)
#define pi M_PI
 
typedef long long ll;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef vector<VI> VVI;
typedef pair<int,int> P;
typedef pair<ll,ll> PL;

int main() {
    int w, h;
    int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1};
    while (cin >> w >> h && h){
        int d[30][30] = {}, wx[30][30], wy[30][30];
        REP(i,2*h-1){
            if (i % 2 == 0){
                REP(j,w-1) cin >> wy[i/2][j];
            }else{
                REP(j,w) cin >> wx[i/2][j];
            }
        }
        d[0][0] = 1;
        queue<P> que;
        que.push(make_pair(0, 0));
        while (!que.empty()){
            P p = que.front();
            que.pop();
            int x = p.first, y = p.second;
            REP(k,4){
                int i = x+dx[k], j = y+dy[k];
                if (i<0 || j<0 || i>=h || j>=w || d[i][j] > 0) continue;
                if (k == 0 && wx[x][y]) continue;
                if (k == 1 && wx[x-1][y]) continue;
                if (k == 2 && wy[x][y]) continue;
                if (k == 3 && wy[x][y-1]) continue;
                d[i][j] = d[x][y] + 1;
                que.push(make_pair(i, j));
            }
        }
        cout << d[h-1][w-1] << endl;
    }

    return 0;
}