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<vector>
#define INF 10000000
#define N 101
using namespace std;

int n,M[N][N],d[N];
void dijkstra(int s){
  int use[N],min,u;
  for(int i=0;i<n;i++) use[i]=0,d[i]=INF;
  d[s]=1;
      while(1){
    min=INF;
    for(int i=0;i<n;i++) if(use[i]!=1 && d[i]<min ) min=d[i],u=i;
    if(min==INF) break;
        use[u]=1;
    for(int i=0;i<n;i++)
      if(use[i]!=1 && M[u][i]!=INF)
	if(d[u]+M[u][i]<d[i])
	  d[i]=d[u]+M[u][i];
    }
}

int main(){
  while(1){
  vector<int> wallh,wallw;
  int h,w,wall;
  cin>>w>>h;
  if(w+h==0) break;
  n=w*h;
  for(int i=0;i<N;i++)
    for(int j=0;j<N;j++) M[i][j]=INF;
  for(int i=0;i<w*h;i++){
    M[i][i+1]=1,M[i][i+w]=1;
    if(i-1>=0) M[i][i-1]=1;
    if(i-w>=0) M[i][i-w]=1;
  }
    
  int cntw=0,cnth=0;
  for(int i=0;i<(w*(h-1))+((w-1)*h);i++){
    cin>>wall;
    if(cntw==w-1 && cnth<=w)  wallh.push_back(wall),cnth++;
    else if(cnth==0 && cntw<w)  wallw.push_back(wall),cntw++;
      if(cntw==w-1 && cnth==w) cntw=0,cnth=0;
  }
  int cnt=0;
   for(int i=0;i<wallw.size();i++){
     if((i+cnt+1)%w==0){
       M[i+cnt][i+1+cnt]=INF;
       M[i+1+cnt][i+cnt]=INF;
       cnt++;
     }
     if(wallw[i]==1) M[i+cnt][1+i+cnt]=INF,M[i+1+cnt][i+cnt]=INF;
   }   
   for(int i=0;i<wallh.size();i++) if(wallh[i]==1)M[i][i+w]=INF,M[i+w][i]=INF;
       dijkstra(0);
       if(d[w*h-1]==INF) d[w*h-1]=0;
    cout<<d[w*h-1]<<endl;
    wallh.clear(),wallw.clear();
  }
   return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<queue>
#include<map>
using namespace std;
#define INF ( 1 << 30 )
#define fr first
#define sc second
typedef pair< int , int > Pt;
const int dx[] = { 0, 1, -1, 0}, dy[] = { 1, 0, 0, -1};
int w, h, cost[30][30];
bool mas[30][30][30][30];
int bfs(){
  fill_n(cost[0],900,0);
  queue<Pt> que;
  cost[0][0] = 1;
  que.push(Pt(0,0));
  while(!que.empty()){
    Pt p = que.front();
    que.pop();
    if(p.fr == h - 1 && p.sc == w - 1) break;
    for(int i = 0 ; i < 4 ; i++ ){
      int ny = p.fr + dy[i], nx = p.sc + dx[i];
      if(ny >= 0 && ny < h && nx >= 0 && nx < w && !cost[ny][nx] && !mas[p.fr][p.sc][ny][nx]){
        cost[ny][nx] = cost[p.fr][p.sc] + 1;
        que.push(Pt(ny,nx));
      }
    }
  }
  return cost[h-1][w-1];
}
int main(){
  while(cin >> w >> h , w){
    for(int i = 0 ; i < 2 * h - 1 ; i++ ){
      if(i % 2)
        for(int j = 0 ; j < w ; j++ ) cin >> mas[i/2][j][i/2+1][j];
      else
        for(int j = 0 ; j < w - 1 ; j++ ) cin >> mas[i/2][j][i/2][j+1];
    }
    cout << bfs() << endl;
  }
}

C++: #include <bits/stdc++.h>
typedef long long ll;
using namespace std;
#define repr(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define invrepr(i,a,b) for(int i=b-1;i>=a;i--)
#define invrep(i,n) invrepr(i,0,n)
#define repitr(itr,a) for(auto itr=a.begin();itr!=a.end();++itr)
const ll MOD=1e9+7;

int main() {
    ios_base::sync_with_stdio(false);

    while (1) {
        int w,h;
        cin >> w >> h; 
        if (w==0 && h==0) break;
        vector<vector<int>> d(w*h,vector<int>(w*h));
        rep(i,2*h-1) {
            if (i%2==0) {
                rep(j,w-1) {
                    int k;
                    cin >> k;
                    if (k==1) {
                        d[w*(i/2)+j][w*(i/2)+j+1]=1;
                        d[w*(i/2)+j+1][w*(i/2)+j]=1;
                    }
                }
            } else {
                rep(j,w) {
                    int k;
                    cin >> k;
                    if (k==1) {
                        d[w*(i/2)+j][w*(i/2)+j+w]=1;
                        d[w*(i/2)+j+w][w*(i/2)+j]=1;
                    }
                } 
            }
        }
        queue<int> q;
        q.push(0);
        vector<int> di={-1,0,0,1},dj={0,-1,1,0};
        vector<int> cost(w*h);
        cost[0]=1;
        while (!q.empty()) {
            int now=q.front();
            q.pop();
            rep(i,4) {
                int ni=now/w+di[i],nj=now%w+dj[i];
                if (ni>=0 && ni<h && nj>=0 && nj<w) {
                    int next=ni*w+nj;
                    if (cost[next]==0 && d[now][next]==0) {
                        cost[next]=cost[now]+1;
                        q.push(next);
                    }
                }
            }
        }
        cout << cost[w*h-1] << endl;
    }
    
    return 0;
}