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<iostream>
#include<vector>
#include<algorithm>
#include<set>
#include<queue>
using namespace std;
#define F first
#define S second
typedef pair<int,int>pii;
typedef pair<int,pii>piii;
typedef pair<pii,pii>piiii;
const int INF=1e9+7;
const int dx[]={0,-1,0,1};
const int dy[]={-1,0,1,0};
int main(){
    int w,h;
    while(cin>>w>>h,w||h){
        set<piiii>W;

        for(int i=0;i<2*h-1;i++){
            for(int j=0;j<w-1+(i&1);j++){
                int v;cin>>v;
                if(v==0)continue;
                int y1,y2,x1,x2;
                if(i&1){
                    y1=i/2;y2=y1+1;x1=x2=j;
                }
                else{
                    y1=y2=i/2;x1=j;x2=x1+1;
                }
                W.insert(piiii(pii(y1,x1),pii(y2,x2)));
                W.insert(piiii(pii(y2,x2),pii(y1,x1)));
            }
        }

        int d[64][64];fill_n(*d,64*64,INF);
        queue<piii>Q;Q.push(piii(0,pii(0,0)));
        while(Q.size()){
            piii p=Q.front();Q.pop();
            int y=p.S.F,x=p.S.S,cnt=p.F;
            if(y<0||y>=h||x<0||x>=w)continue;
            if(d[y][x]!=INF)continue;
            d[y][x]=cnt;
            for(int i=0;i<4;i++){
                if(W.find(piiii(pii(y,x),pii(y+dy[i],x+dx[i])))!=W.end())continue;
                Q.push(piii(cnt+1,pii(y+dy[i],x+dx[i])));
            }
        }
        if(d[h-1][w-1]==INF)cout<<0<<endl;
        else cout<<d[h-1][w-1]+1<<endl;
    }
    return 0;
}

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;
  }
}