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 mem[60][60], H, W, dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};
int d[30][30];
int main()
{
loop:
  for(int i = 0; i < 30; i++)
    for(int j = 0; j < 30; j++)
      d[i][j] = 0;
  
  cin >> W >> H;
  if(!W)
    return 0;
  for(int i = 0; i < H * 2 - 1; i++)
  {
    for(int j = 0; j < W  - (i + 1) % 2; j++)
    {
      cin >> mem[i][j];
    }
  }
  d[0][0] = 1;
  queue<int> q;
  q.push(0); q.push(0);
  while(!q.empty())
  {
    int x = q.front(); q.pop();
    int y = q.front(); q.pop();
    if(x == W - 1 && y == H - 1)
    {
      cout << d[y][x] << endl;
      goto loop;
    }
    for(int i = 0; i < 4; i++)
    {
      int tx = x + dx[i];
      int ty = y + dy[i];
      if(tx >= 0 && tx < W && ty >= 0 && ty < H && !d[ty][tx])
      {
        if(dx[i] == 1 && !mem[y * 2][x] ||
           dx[i] == -1 && !mem[y * 2][tx] ||
           dy[i] == 1 && !mem[y * 2 + 1][x] ||
           dy[i] == -1 && !mem[ty * 2 + 1][x])
        {
          q.push(tx); q.push(ty);
          d[ty][tx] = d[y][x] + 1;
        }
      }
    }
  }
  cout << 0 << endl;
  goto loop;
}

C++: #include<iostream>
#include<vector>
#include<queue>
using namespace std;

int memo[1024][1024];

int main() {
  for(;;) {
  int R, C;
  cin >> C >> R >> ws;
  if( C == 0 && R == 0 ) break;
  C = C * 2 - 1;
  R = R * 2 - 1;

  vector<string> vs;
  for(int i = 0; i < R; i++) {
    string line;
    getline(cin, line);
    vs.push_back(line);
  }
    
  memset(memo, -1, sizeof(memo));
  memo[0][0] = 1;
  queue<int> q;
  q.push(0);  q.push(0);
  while( !q.empty() ) {
    int x = q.front(); q.pop();
    int y = q.front(); q.pop();
    
    const int dx[] = {0, 0, 1, -1};
    const int dy[] = {1, -1, 0, 0};

    for(int k = 0; k < 4; k++) {
      int nx = x + dx[k];
      int ny = y + dy[k];

      if( 0 <= nx && nx < R && 0 <= ny && ny < C ) {
        if( vs[nx][ny] == '0' ) {
          nx += dx[k];
          ny += dy[k];

          if( memo[nx][ny] == -1 ) {
            memo[nx][ny] = memo[x][y] + 1;
            q.push(nx);
            q.push(ny);
          }
          
        }
      }
      
    }
    
  }
  
  int res = memo[R - 1][C - 1];
  if( res == -1 ) res = 0;

  cout << res << endl;
  }
  return 0;
}

C++: #include <iostream> 
#include <string> 
#include <vector> 
#include <cmath> 
#include <algorithm> 
#include <cstdlib> 
#include <ctime> 
#include <cstdio> 
#include <functional> 
#include <set> 
#include <sstream> 
#include <queue>

using namespace std; 

typedef pair<int,int> P;

int W,H;

bool pass[900][900];

//スタートからの距離
int d[50][50];

//上下左右
const int dw[4]={0,0,-1,1};
const int dh[4]={-1,1,0,0};

const int INF=10000;


void bfs(){
	queue<P> que;
	for(int i=0;i<50;i++){
		for(int j=0;j<50;j++){
			d[i][j]=INF;
		}
	}
	que.push(P(0,0));
	d[0][0]=1;

	while(!que.empty()){
		int h,w;
		h=que.front().first;
		w=que.front().second;
		que.pop();
		if(h==H-1 && w==W-1) break;


		for(int i=0;i<4;i++){
			//隣の座標
			int nh=h+dh[i];
			int nw=w+dw[i];

			//現在，次の頂点番号
			int n=W*h+w;
			int m=W*nh+nw;

			if(0<=nh && nh<H && 0<=nw && nw<W && pass[n][m] && d[nh][nw]==INF){
				que.push(P(nh,nw));
				d[nh][nw]=d[h][w]+1;
			}

		}

	}

}


int main(){



	while(cin>>W>>H,W){

		for(int i=0;i<900;i++)
			for(int j=0;j<900;j++) pass[i][j]=false;



		//マップ読み込み
		for(int i=0;i<2*H-1;i++){
			//右に移動が可能か
			if(i%2==0){
				for(int j=0;j<W-1;j++){
					int c;
					cin>>c;

					int h=i/2,w=j;
					if(c==0){
						 pass[W*h+w][W*h+(w+1)]=pass[W*h+(w+1)][W*h+w]=true;
					}
				}
			}//下に移動が可能か
			else{
				for(int j=0;j<W;j++){
					int c;
					cin>>c;

					int h=i/2,w=j;
					if(c==0){
						 pass[W*h+w][W*(h+1)+w]=pass[W*(h+1)+w][W*h+w]=true;
					}
				}
			}
		}


		bfs();
		if(d[H-1][W-1]==INF) d[H-1][W-1]=0;
		cout<<d[H-1][W-1]<<endl;

	}

	return 0;
}