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<bits/stdc++.h>

#define _GLIBCXX_DEBUG
#define all(v) (v).begin(),(v).end()

using namespace std;

using ll=long long;
using pii=pair<int, int>;
using vi=vector<int>;

const ll INF=1LL<<60;
const int MOD=1e9+7;

int dx[]={1, 0, -1, 0};
int dy[]={0, 1, 0, -1};

int main(){
    int w, h;
    while(cin >> w >> h){
        if(w == 0 && h == 0) break;
        vector<vector<vi>> mn(h, vector<vi>(w, vi(4, 1)));
        for(int i=0; i<2*h-1; i++){
            for(int j=(i+1)%2; j<w; j++){
                int x; cin >> x;
                if(x == 0) continue;
                if(i%2 == 0){
                    mn[i/2][j-1][1]=0;
                    mn[i/2][j][3]=0;
                }
                else{
                    mn[i/2][j][0]=0;
                    mn[i/2+1][j][2]=0;
                }
            }
        }
        queue<pii> que;
        vector<vi> dist(h, vi(w, 0));
        que.push({0, 0});
        dist[0][0]=1;
        while(!que.empty()){
            int x, y;
            tie(x, y)=que.front();
            que.pop();
            for(int i=0; i<4; i++){
                int nx, ny;
                nx=x+dx[i], ny=y+dy[i];
                if(nx<0 || nx>=h || ny<0 || ny>=w) continue;
                if(mn[x][y][i] == 0) continue;
                if(dist[nx][ny] != 0) continue;
                dist[nx][ny]=dist[x][y]+1;
                que.push({nx, ny});
            }
        }
        cout << dist[h-1][w-1] << endl;
    }
    return 0;
}

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

using namespace std;
using P = pair<int,int>;

enum dir{
  RIGHT = 1,
  DOWN = 2,
  LEFT = 4,
  UP = 8
};

int map[30][30];
int visited[30][30];
int dist[30][30];

int main(){
  int w,h;
  while(cin >> w >> h&&w>0&&h>0){
    for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
        map[i][j] = 0;
        visited[i][j] = 0;
        dist[i][j] = 0;
      }
    }

    for(int i=0;i<h;++i){
      map[i][0] |= LEFT;
      map[i][w-1] |= RIGHT;
    }

    for(int j=0;j<w;++j){
      map[0][j] |= UP;
      map[h-1][j] |= DOWN;
    }

    for(int i=0;i<2*h-1;++i){
      for(int j=0;j<w-1+i%2;++j){
        int wall;
        cin >> wall;
        if(wall){
          if(i%2){
            map[i/2][j] |= DOWN;
            map[i/2+1][j] |= UP;
          }else{
            map[i/2][j] |= RIGHT;
            map[i/2][j+1] |= LEFT;
          }
        }
      }
    }
    
    queue<P> q;
    q.push(P(0,0));
    visited[0][0] = 1;
    dist[0][0] = 1;
    while(!q.empty()){
      auto p = q.front();q.pop();
      int y = p.first , x = p.second;
      if(!((map[y][x]&RIGHT)||visited[y][x+1])){
        q.push(P(y,x+1));
        dist[y][x+1] = dist[y][x]+1;
        visited[y][x+1] = 1;
      }
      if(!((map[y][x]&DOWN)||visited[y+1][x])){
        q.push(P(y+1,x));
        dist[y+1][x] = dist[y][x]+1;
        visited[y+1][x] = 1;
      }
      if(!((map[y][x]&LEFT)||visited[y][x-1])){
        q.push(P(y,x-1));
        dist[y][x-1] = dist[y][x]+1;
        visited[y][x-1] = 1;
      }
      if(!((map[y][x]&UP)||visited[y-1][x])){
        q.push(P(y-1,x));
        dist[y-1][x] = dist[y][x]+1;
        visited[y-1][x] = 1;
      }

    }
/*
    for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
        cout << setw(4) << map[i][j];
      }
      cout << endl;
    }
   
    for(int i=0;i<h;++i){
      for(int j=0;j<w;++j){
        cout << setw(4) << dist[i][j];
      }
      cout << endl;
    }*/
    cout << dist[h-1][w-1] << endl;

  }

}