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 <algorithm>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using std::cerr;
using std::cin;
using std::cout;
using std::endl;
typedef std::pair<int,int> Pos;

struct State{
  int row,column,depth;
  State(int a,int b,int c){
    row=a;
    column=b;
    depth=c;
  }
};

bool map[30][30]={};
int h,w;
std::vector<bool> horizontal_wall[30]={},vertical_wall[30]={};

bool CanMoveEast(State state){
  int row=state.row;
  int column=state.column;
  if(column+1>=w) return false;
  if(horizontal_wall[row][column]) return false;
  if(map[row][column+1]) return false;
  return true;
}

bool CanMoveWest(State state){
  int row=state.row;
  int column=state.column;
  if(column-1<0) return false;
  if(horizontal_wall[row][column-1]) return false;
  if(map[row][column-1]) return false;
  return true;
}

bool CanMoveNorth(State state){
  int row=state.row;
  int column=state.column;
  if(row-1<0) return false;
  if(vertical_wall[row-1][column]) return false;
  if(map[row-1][column]) return false;
  return true;
}

bool CanMoveSouth(State state){
  int row=state.row;
  int column=state.column;
  if(row+1>=h) return false;
  if(vertical_wall[row][column]) return false;
  if(map[row+1][column]) return false;
  return true;
}


int main(void) {
  cout << std::fixed << std::setprecision(10);
  cin.tie(0);
  std::ios::sync_with_stdio(false);



  cin>>w>>h;


  for(int i=0;i<2*h-1;i++){
    if(i%2==0){
      for(int j=0;j<w-1;j++){
        bool temp;
        cin>>temp;
        horizontal_wall[i/2].push_back(temp);
      }
    }else{
      for(int j=0;j<w;j++){
        bool temp;
        cin>>temp;
        vertical_wall[i/2].push_back(temp);
      }
    }
  }

  std::queue<State> bfs_queue;
  bfs_queue.push(State(0,0,1));
  while (!bfs_queue.empty()){
    State next_state=bfs_queue.front();
    int row=next_state.row,column=next_state.column,depth=next_state.depth;
    bfs_queue.pop();
    if(row==h-1&&column==w-1){
      cout<<depth<<endl;
      return 0;
    }
    map[next_state.row][next_state.column]=true;
    if(CanMoveEast(next_state)){
      bfs_queue.push(State(row,column+1,depth+1));
    }
    if(CanMoveNorth(next_state)){
      bfs_queue.push(State(row-1,column,depth+1));
    }
    if(CanMoveSouth(next_state)){
      bfs_queue.push(State(row+1,column,depth+1));
    }
    if(CanMoveWest(next_state)){
      bfs_queue.push(State(row,column-1,depth+1));
    }

  }
  cout<<0<<endl;


  return 0;
}