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 rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define SIZE 200005
#define INF 1000000005LL
#define MOD 1000000007

using namespace std;
typedef long long int ll;
typedef pair <int,int> P;

int h,w;

void bfs(){
  vector<vector<int>> v(h*w);
  vector<int> d(h*w,-1);
  rep(i,0,2*h-1){
    if(i%2==0){
      rep(j,0,w-1) {
        int c;
        cin >> c;
        if(c==0){
          v[(i/2)*w+j].push_back((i/2)*w+j+1);
          v[(i/2)*w+j+1].push_back((i/2)*w+j);
        }
      }
    }else{
      rep(j,0,w){
        int c; cin >> c;
        if(c==0){
          v[(i/2)*w+j].push_back(((i/2)+1)*w+j);
          v[(i/2+1)*w+j].push_back((i/2)*w+j);
        }
      }
    }
  }
  queue<int> q;
  q.push(0);
  d[0] = 1;
  while(!q.empty()){
    int u = q.front();q.pop();
    for(int nt : v[u]) if(d[nt] == -1){
      d[nt] = d[u]+1;
      q.push(nt);
    }
  }
  cout << max(0,d[h*w-1]) << endl;
}


int main(){
  for(;;){
    cin >> w >> h;
    if(h==0 && w==0)break;
    bfs();
  }

  return 0;
}

C++: #include "bits/stdc++.h"

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef vector<int> VI;
typedef vector<VI> VVI;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const int INF = numeric_limits<int>::max() / 2;
const int NEG_INF = numeric_limits<int>::min() / 2;
const int MOD = 1e9 + 7;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

    int w,h;
    while(cin>>w>>h,w||h){
        vector< vector<int> > dis(1000,vector<int>(1000,INF));
        for(int i=0;i<1000;i++){
            dis[i][i]=0;
        }
        for(int i=0;i<2*h-1;i++){
            if(i%2==0){// ?¨??£?
                for(int j=0;j<w-1;j++){
                    int k;cin>>k;
                    int y=j,x=i/2;
                    if(k) continue;
                    dis[x*w+y][x*w+y+1]=dis[x*w+y+1][x*w+y]=1;
                }
            }
            else{
                for(int j=0;j<w;j++){
                    int k;cin>>k;
                    int y=j,x=i/2;
                    if(k) continue;
                    dis[x*w+y][x*w+y+w]=dis[x*w+y+w][x*w+y]=1;
                }
            }
        }
        int p=w*h;
        for(int k=0;k<p;k++){
            for(int i=0;i<p;i++){
                for(int j=0;j<p;j++){
                    dis[i][j]=min(dis[i][k]+dis[k][j],dis[i][j]);
                }
            }
        }
        if(dis[0][p-1]==INF) cout<<0<<endl;
        else cout<<dis[0][p-1]+1<<endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <map>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>
#include <list>
#include <stack>
#include <queue>
using namespace std;

typedef list<int> L;
typedef pair <int,int> P;
typedef vector<int> V;
typedef queue<P> Q;
typedef stack<int> S;
typedef map<string,int> M;

int W, H;
const int MAX = 31;
const int INF = 99999;
int dx[] = {0, 1, 0, -1}, dy[] = {-1, 0, 1, 0};
int ds[] = {1, 2, 4, 8};

int bfs(int s[MAX][MAX]) {
    Q q;
    q.push(P(0, 0));
    int d[MAX][MAX];
    for (int i = 0; i < MAX; i++)
        for (int j = 0; j < MAX; j++)
            d[i][j] = INF;
    d[0][0] = 1;

    while (q.size()) {
        int x = (q.front()).first, y = (q.front()).second;
        q.pop();

        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (0 <= nx && nx < H && 0 <= ny && ny < W && d[nx][ny] == INF && (s[x][y] & ds[i]) == 0) {
                q.push(P(nx, ny));
                d[nx][ny] = d[x][y] + 1;
            }
        }
    }

    return d[H - 1][W - 1] != INF ? d[H - 1][W - 1] : 0;
}

int main()
{
    while (cin >> W >> H, H) {
        int s[MAX][MAX] = {};
        for (int i = 0; i < H; i++) {
            for (int j = 1; j < W; j++) {
                int wall; cin >> wall;
                if (wall == 1) {
                    s[i][j] |= 1;
                    s[i][j - 1] |= 4;
                }
                if (j == 1)
                    s[i][j - 1] |= 1;
                else if (j == W - 1)
                    s[i][j] |= 4;
            }
            for (int j = 0; j < W; j++) {
                int wall;
                if (i < H - 1) cin >> wall;
                else wall = 1;
                if (wall == 1) {
                    s[i][j] |= 2;
                    s[i + 1][j] |= 8;
                }
                if (i == 0)
                    s[i][j] |= 8;
            }
        }
        cout << bfs(s) << endl;;

    }

    return 0;
}