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<algorithm>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<string>
#include<sstream>
#include<cmath>
#include<numeric>
#include<map>
#include<stack>
#include<queue>
#include<cassert>
using namespace std;
int inf = 1000000000;

int main(void) {
  int dx[4] = {0, 0, 1, -1};
  int dy[4] = {1, -1, 0, 0};
  int w, h;
  while( cin >> w >> h ){
    if( w == 0 && h == 0 ) break;
    vector<string> s(2*h-1);
    cin.ignore();
    for(int i=0; i<s.size(); i++) getline(cin, s[i]);

    // for(int i=0; i<s.size(); i++) cerr << s[i] << endl;

    queue< pair<int, int> > q;
    q.push( make_pair(0, 0) );
    vector< vector<int> > cost(2*h-1, vector<int> (2*w-1, inf));
    cost[0][0] = 1;

    while( !q.empty() ){
      pair<int, int> p = q.front();
      q.pop();

      for(int dir=0; dir<4; dir++){
        int nx = p.second + dx[dir];
        int ny = p.first + dy[dir];

        if( nx < 0 || ny < 0 || nx >= 2*w-1 || ny >= 2*h-1 ) continue;
        if( s[ ny ][ nx ] == '1' ) continue;
        s[ny][nx] = '1';
        nx += dx[dir];
        ny += dy[dir];
        if( nx < 0 || ny < 0 || nx >= 2*w-1 || ny >= 2*h-1 ) continue;
        cost[ny][nx] = cost[p.first][p.second]+1;
        q.push( make_pair(ny, nx) );

      }
    }

    // for(int i=0; i<2*h-1; i++){
    //   for(int j=0; j<2*w-1; j++){
    //     cerr << cost[i][j] << " ";
    //   }
    //   cerr << endl;
    // }
    if( cost[2*h-2][2*w-2] == inf ) cout << 0 << endl;
    else cout << cost[2*h-2][2*w-2] << endl;

  }


  return 0;
}


// EOF

C++: #include <iostream>
#include <queue>

using namespace std;

struct Point {
  int x, y, dist;
};

int main() {
  int w, h;
  while(1) {
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    int lr[h][w], td[h][w];
    for(int i = 0; i < h; i++) {
      for(int j = 0; j < w; j++) {
	lr[i][j] = td[i][j] = 0;
      }
    }
    for(int i = 0; i < h; i++) {
      for(int j = 0; j < w-1; j++) {
	cin >> lr[i][j];
      }
      if(i == h-1) break;
      for(int j = 0; j < w; j++) {
	cin >> td[i][j];
      }
    }


    bool visited[h][w];
    for(int i = 0; i < h; i++)
      for(int j = 0; j < w; j++)
	visited[i][j] = false;

    Point p;
    p.x = 0;
    p.y = 0;
    p.dist = 0;

    queue<Point> Q;
    Q.push(p);

    int ans = -1;

    while(!Q.empty()) {
      int d[4][2] = {{1,0}, {0,1}, {-1,0}, {0,-1}};

      p = Q.front();
      Q.pop();
      visited[p.y][p.x] = true;
      if(p.x == w-1 && p.y == h-1) {
	ans = p.dist;
	break;
      }

      for(int i = 0; i < 4; i++) {
	if(lr[p.y][p.x] && i == 0) continue;
	if(p.x-1 >= 0 && lr[p.y][p.x-1] && i == 2) continue;
	if(td[p.y][p.x] && i == 1) continue;
	if(p.y-1 >= 0 && td[p.y-1][p.x] && i == 3) continue;

	int nx = p.x + d[i][0];
	int ny = p.y + d[i][1];
	if(nx < 0 || nx >= w || ny < 0 || ny >= h) continue;

        if(visited[ny][nx]) continue;

	Point temp;
	temp.x = nx;
        temp.y = ny;
	temp.dist = p.dist + 1;
	Q.push(temp);
	visited[ny][nx] = true;
      }
    }
    if(ans != -1) cout << ans + 1 << endl;
    else cout << 0 << endl;
  }
  return 0;
}

C++: #include<queue>
#include<algorithm>
#include<iostream>
#include<string>
#include<cstdlib>
#include<cstring>
#include<cmath>
using namespace std;
int main(){
  int i,j;
  int a[31][30],b[30][31],d[30][30],p,w,h,x,y;
  queue<pair<pair<int,int>,int> > c;
  while(cin>>w>>h&&w+h){
    memset(a,-1,sizeof(a));
    memset(b,-1,sizeof(b));
    for(j=1;j<w;j++){
      cin>>a[j][0];
      a[j][0]=-a[j][0];
    }
    for(i=1;i<h;i++){    
      for(j=0;j<w;j++){
	cin>>b[j][i];
	b[j][i]=-b[j][i];
      }
      for(j=1;j<w;j++){
	cin>>a[j][i];
	a[j][i]=-a[j][i];
      }
    }
    memset(d,-1,sizeof(d));
    x=y=0;
    while(c.empty()==0)
      c.pop();
    c.push(make_pair(make_pair(x,y),1));
    while(c.empty()==0){
      x=c.front().first.first;
      y=c.front().first.second;
      p=c.front().second;
      if(x==w-1&&y==h-1)
	break;
      c.pop();
      if(d[x][y]==-1||d[x][y]>p){
	d[x][y]=p;
	if(a[x][y]==0)
	  c.push(make_pair(make_pair(x-1,y),p+1));
	if(a[x+1][y]==0)
	  c.push(make_pair(make_pair(x+1,y),p+1));
	if(b[x][y]==0)
	  c.push(make_pair(make_pair(x,y-1),p+1));
	if(b[x][y+1]==0)
	  c.push(make_pair(make_pair(x,y+1),p+1));
      }
    }
    if(c.empty())
      cout<<0<<endl;
    else
      cout<<p<<endl;
  }
  return 0;
}