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 <cstdio>
#include <cstring>
#include <climits>
using namespace std;

int min(int a,int b){return a<b?a:b;}
int max(int a,int b){return a>b?a:b;}
int mv[4][2]={{0,-1},{1,0},{0,1},{-1,0}};
int map[100][100],n,m,N,M;
bool B[100][100];
int q[15000][2];
//unsigned 
int dis[100][100];
void fill(){
    int l=0,r=0;
    q[0][0]=1;q[0][1]=1;B[1][1]=true;
    dis[1][1]=2;
    while(l<=r){
        int x=q[l][0],y=q[l][1];
        int z=dis[x][y];
        for(int i=0;i<4;i++){
            int xx=x+mv[i][0],yy=y+mv[i][1];
            if(map[xx][yy]==-1)continue;
            if(dis[xx][yy]>z+1){
                dis[xx][yy]=z+1;
                if(!B[xx][yy]){
                    B[xx][yy]=true;
                    r++;
                    q[r][0]=xx;
                    q[r][1]=yy;
                }
            }
        }
        l++;
        B[x][y]=false;
    }
}
int main(){
    while(scanf("%d %d",&m,&n),n*m){
        N=2*n+1;M=2*m+1;
        /*
        memset(B,0,sizeof(bool)*10000);
        memset(map,0,sizeof(int)*10000);
        memset(dis,127,sizeof(unsigned int)*10000);
        */
        for(int i=0;i<100;i++)
            for(int j=0;j<100;j++){
                B[i][j]=0;
                map[i][j]=0;
                dis[i][j]=100000;
            }
        for(int i=0;i<N;i++){
            map[i][0]=-1;
            map[i][M-1]=-1;
        }
        for(int i=0;i<M;i++){
            map[0][i]=-1;
            map[N-1][i]=-1;
        }
        int x=1;
        for(int i=0;i<n;i++){
            int y=1;
            if(i){
                for(int j=0;j<m;j++,y+=2){
                    int z;
                    scanf("%d",&z);
                    map[x][y]=-z;
                }
                x++; 
            }
            y=2;
            for(int j=0;j<m-1;j++,y+=2){
                int z;
                scanf("%d",&z);
                map[x][y]=-z;
            }
            x++;
        }
        for(int i=0;i<n;i++)
            for(int j=0;j<m;j++)
                map[i*2][j*2]=-1;
        fill();
        int ans=dis[N-2][M-2]/2;
        if(ans>=50000)ans=0;
        printf("%d\n",ans);
/*        
        printf("%d %d\n",N,M);
        for(int i=0;i<N;i++){
            for(int j=0;j<M;j++){
                //if(dis[i][j]>=20000)dis[i][j]=0;
                //printf("%d ",dis[i][j]);
                printf("%d ",map[i][j]*-1);
            }
            printf("\n");
        }
*/ 
    }
    return 0;
}

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

const int MAX = 30;
typedef pair<int,int> P;

int H,W;
int dist[MAX+1][MAX+1];
bool wall[MAX+1][MAX+1][4];
int dy[4] = {-1,0,1,0};
int dx[4] = {0,1,0,-1};

int bfs(){
  queue<P> Que;
  Que.push(P(0,0));

  memset(dist,0,sizeof(dist));
  dist[0][0] = 1;
  
  while(!Que.empty()){
    P p = Que.front(); Que.pop(); 
    int y = p.first, x = p.second;

    for(int i = 0 ; i < 4 ; i++){
      int nx = x + dx[i];
      int ny = y + dy[i];
 
      if(0 <= nx && nx < W && 0 <= ny && ny < H && 
	 !wall[y][x][i] && !dist[ny][nx]){
	dist[ny][nx] = dist[y][x] + 1;
	Que.push(P(ny,nx));
      }
    }
  }

  return dist[H-1][W-1];
}

int main(){
  while(cin >> W >> H , W | H){
    memset(wall,false,sizeof(wall));

    int t;
    for(int i = 0 ; i < H ; i++){
      for(int j = 0 ; j < W - 1 ; j++){
	cin >> t;      
	wall[i][j][1] = wall[i][j+1][3] = t;
      }
      if(i < H-1){
	for(int j = 0 ; j < W ; j++){
	  cin >> t;
	  wall[i][j][2] = wall[i+1][j][0] = t;
	}
      }
    }
    
    cout << bfs() << endl;
  }

  return 0;
}