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<queue>

using namespace std;

int main() {
	int w, h;
	while(1){
		cin >> w >> h;
		if (w == 0)break;
		int** kabe = new int* [2 * h - 1];
		for (int i = 0;i < 2 * h - 1;i++) {
			kabe[i] = new int[w - 1 + i%2];
			for (int j = 0;j < w - 1 +i%2;j++) {
				cin >> kabe[i][j];
			}
		}
		int** dist = new int*[h];
		for (int i = 0;i < h;i++) {
			dist[i] = new int[w];
			for (int j = 0;j < w;j++) {
				dist[i][j] = -1;
			}
		}
		queue<pair<int, pair<int, int> > > q;
		q.push(make_pair(0, make_pair(0, 0)));
		dist[0][0] = 0;
		while (!q.empty()) {
			pair<int, pair<int, int> > p = q.front();
			q.pop();
			int y = p.second.first;
			int x = p.second.second;
			if (y > 0) {
				if (dist[y-1][x] == -1 && kabe[2*y-1][x]==0){
					q.push(make_pair(p.first + 1, make_pair(y - 1, x)));
					dist[y - 1][x] = p.first + 1;
				}
			}
			if (y < h-1) {
				if (dist[y + 1][x] == -1 && kabe[2 * y + 1][x] == 0) {
					q.push(make_pair(p.first + 1, make_pair(y + 1, x)));
					dist[y + 1][x] = p.first + 1;
				}
			}
			if (x > 0) {
				if (dist[y][x-1] == -1 && kabe[2 * y][x - 1] == 0) {
					q.push(make_pair(p.first + 1, make_pair(y , x-1)));
					dist[y][x-1] = p.first + 1;
				}
			}
			if (x <w-1) {
				if (dist[y][x+1] == -1 && kabe[2 * y][x] == 0) {
					q.push(make_pair(p.first + 1, make_pair(y, x+1)));
					dist[y][x + 1] = p.first + 1;
				}
			}

		}
		cout << dist[h - 1][w - 1] + 1 << endl;
	}
	
	
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

int **wall_h;
int **wall_v;
int **tile;
int w,h;

void dfs(int x,int y,int depth);

int main(){
	while(1){
		cin >> w >> h ;
		if(!w){
			break;
		}
		wall_h = new int*[w];
		wall_v = new int*[w];
		for (int i=0;i<w;i++){
			wall_h[i] = new int[h];
			wall_v[i] = new int[h];
		}
		
		for (int i=0; i<h-1; i++) {
			for (int j=0; j<w-1; j++) {
				cin >> wall_v[j][i];
			}
			wall_v[w-1][i] = 1;
			for (int j=0; j<w; j++) {
				cin >> wall_h[j][i];
			}
		}
		for (int j=0; j<w-1; j++) {
			cin >> wall_v[j][h-1];
		}
		wall_v[w-1][h-1] = 1;
		for (int j=0; j<w; j++) {
			wall_h[j][h-1] = 0;
		}
		
		tile = new int*[w];
		for (int i=0; i<w; i++) {
			tile[i] = new int[h];
			for (int j=0; j<h; j++) {
				tile[i][j] = 0;
			}
		}
		dfs(0,0,1);

		cout << tile[w-1][h-1] << endl;
		
		
		for (int i=0; i<w; i++) {
			delete [] tile[i];
			delete [] wall_v[i];
			delete [] wall_h[i];
		}
		delete [] tile;
		delete [] wall_v;
		delete [] wall_h;
	}
	return 0;
}

void dfs(int x,int y,int depth){
	if (tile[x][y] == 0 || tile[x][y] > depth) {
		tile[x][y] = depth;
		if (x != 0 && wall_v[x-1][y] == 0) {
			dfs(x-1,y,depth+1);
		}
		if (x!=w-1 && wall_v[x][y] == 0) {
			dfs(x+1,y,depth+1);
		}
		if (y!=0 && wall_h[x][y-1] ==0) {
			dfs(x,y-1,depth+1);
		}
		if (y!=h-1 && wall_h[x][y] ==0) {
			dfs(x,y+1,depth+1);
		}
	}
	return;
	
}

C++: #include<queue>
#include<math.h>
#include<cmath>
#include<bitset>
#include<stdio.h>
#include<string>
#include<map>
#include<algorithm>
#include<vector>
#include<iostream>
#include<utility>
using namespace std;
int main(){
  int INF=(1<<29);
  queue<int> q1,q2;
  int i,j,x,y,w,h,b[100][100],a[100][100];
  while(1){
    scanf("%d %d\n",&w,&h);
    if(w==0 && h==0){
      break;
    }
    for(i=0;i<=h*2;i++){
      for(j=0;j<=w*2;j++){
        a[i][j]=1,b[i][j]=INF;
      }
    }
    for(i=1;i<=h*2-1;i++){
      if(i%2==1){
        for(j=2;j<=w*2-1;j=j+2){
          scanf("%d",&a[i][j]);
        }
      }
      else{
        for(j=1;j<=w*2-1;j=j+2){
          scanf("%d",&a[i][j]);
        }
      }
      scanf("\n");
    }
    b[1][1]=1;
    q1.push(1),q2.push(1);
    while(!q1.empty()){
      x=q1.front(),y=q2.front();
      q1.pop(),q2.pop();
      if(a[x+1][y]==0 && b[x+2][y]>b[x][y]+1){
        b[x+2][y]=b[x][y]+1;
        q1.push(x+2),q2.push(y);
      }
      if(a[x-1][y]==0 && b[x-2][y]>b[x][y]+1){
        b[x-2][y]=b[x][y]+1;
        q1.push(x-2),q2.push(y);
      }
      if(a[x][y+1]==0 && b[x][y+2]>b[x][y]+1){
        b[x][y+2]=b[x][y]+1;
        q1.push(x),q2.push(y+2);
      }
      if(a[x][y-1]==0 && b[x][y-2]>b[x][y]+1){
        b[x][y-2]=b[x][y]+1;
        q1.push(x),q2.push(y-2);
      }
    }
    if(b[h*2-1][w*2-1]==INF){
      printf("0\n");
      continue;
    }
    printf("%d\n",b[h*2-1][w*2-1]);
  }
  return 0;
}