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>
#define MAX 10000000
using namespace std;
#define Rep(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) Rep(i,0,a)
int sum,u[40][40][4],v[40][40];
int w,h;
int dx[]={0,0,-1,1},dy[]={1,-1,0,0},d[40][40];
void func(int x,int y,int now){
		d[y][x]=now;
	if(x!=w-1||y!=h-1){
		rep(i,4)
		if(u[y][x][i]==1&&d[y+dy[i]][x+dx[i]]>now+1)
		func(x+dx[i],y+dy[i],now+1);
	}
}
int main(){
	int box[40][40];
	while(cin>>w>>h,w||h){
		rep(i,2*h-1)
		rep(j,w-1+i%2)
		cin>>box[i][j];
		//1
	   //2 3
		//0
		rep(i,h)
		rep(j,w){
			d[i][j]=MAX;
			if(j==0)
				u[i][0][2]=0;
			else {
				if(box[2*i][j-1]==1)
					u[i][j][2]=0;
				else u[i][j][2]=1;
			}
			if(i==0)
				u[0][j][1]=0;
			else {
				if(box[2*i-1][j]==1)
					u[i][j][1]=0;
				else u[i][j][1]=1;
			}
			if(i==h-1)
				u[h-1][j][0]=0;
			else {
				if(box[2*i+1][j]==1)
					u[i][j][0]=0;
				else u[i][j][0]=1;
			}
			if(j==w-1)
				u[i][w-1][3]=0;
			else {
				if(box[2*i][j]==1)
					u[i][j][3]=0;
				else u[i][j][3]=1;
			}
		}
	func(0,0,1);
	if(d[h-1][w-1]==MAX)
		cout<<'0';
	else cout<<d[h-1][w-1];
	cout<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define MAX 100000
using namespace std;
int W, H;

int xy2l(int x, int y){
  return W*y + x;
}
pair<int, int> l2xy(int l){
  pair<int, int> res;
  res.first = W%l;
  res.second = W/l;
  return res;
}

int main(void){
  ios::sync_with_stdio(false);
  cin.tie(0);
  while(cin >> W >> H, W | H){
    vector< vector<int> > v(H*W, vector<int>(W*H, MAX));
    for(int i = 0; i < 2*H-1; i++){
      if(i % 2 == 0){
        for(int j = 0; j < W-1; j++){
          int wall; cin >> wall;
          if(wall == 0){
            v[xy2l(j, i/2)][xy2l(j+1, i/2)] = 1;
            v[xy2l(j+1, i/2)][xy2l(j, i/2)] = 1;
          }
        }
      }
      if(i % 2 == 1){
        for(int j = 0; j < W; j++){
          int wall; cin >> wall;
          if(wall == 0){
            v[xy2l(j, i/2)][xy2l(j, i/2+1)] = 1;
            v[xy2l(j, i/2+1)][xy2l(j, i/2)] = 1;
          }
        }
      }
    }

    vector<bool> used(H*W, false);
    vector<int> d(H*W, MAX);
    d[0] = 0;
    while(1){
      int s = -1;
      for(int u = 0; u < H*W; u++){
        if(!used[u] && (s == -1 || d[u] < d[s])) s = u;
      }
      if(s == -1) break;
      used[s] = true;
      for(int u=0; u < H*W; u++){
        d[u] = min(d[u], d[s] + v[s][u]);
      }
    }
    //for(int i = 0; i < d.size(); i++) cout << d[i] << endl;
    if(d[d.size()-1] == MAX) cout << 0 << endl;
    else cout << d[d.size()-1]+1 << endl;
  }
  return 0;
}

C++: #include<cstdio>
#include<iostream>
#include<vector>
#include<queue>
#include<functional>
#define rep(i,a,b) for(int (i)=(a);(i)<(b);(i)++)
using namespace std;

#define MAX_V 900
#define E 900
#define INF 10000
int h,w,V;
#define pos(_h,_w) ((_h)*w)+(_w) 
struct edge{int to,cost;};
vector<edge> G[MAX_V];
int d[MAX_V];
typedef pair<int,int>P;

void dk(int s){
	priority_queue<P,vector<P>,greater<P> >que;
	fill(d,d+V,INF);
	d[s]=0;que.push(P(0,s));

	while(!que.empty()){
		P p=que.top();que.pop();
		int v=p.second;
		if(d[v]<p.first)continue;
		rep(i,0,(int)G[v].size()){
			edge e=G[v][i];
			if(d[e.to]>d[v]+e.cost){
			d[e.to]=d[v]+e.cost;
			que.push(P(d[e.to],e.to));
			}
		}
	}
}
 


int main(void){
while(true){
	cin>>w>>h;
	V=h*w;
	if(w==0)return(0);
	rep(i,0,2*h-1){
		int now_h=i/2;
	if(!(i&1))
		rep(j,0,w-1){
			edge temp;cin>>temp.cost;
			if(temp.cost>0)continue;
			temp.cost++;
			temp.to=pos(now_h,j+1);
			G[pos(now_h,j)].push_back(temp);
			temp.to=pos(now_h,j);
			G[pos(now_h,j+1)].push_back(temp);
	}else{
		rep(j,0,w){
			edge temp;cin>>temp.cost;
			if(temp.cost>0)continue;
			temp.cost++;
			temp.to=pos(now_h+1,j);
			G[pos(now_h,j)].push_back(temp);
			temp.to=pos(now_h,j);
			G[pos(now_h+1,j)].push_back(temp);
		}

	}	
	
	}
	dk(0);
	if(d[V-1]>=INF)d[V-1]=0;
	else d[V-1]++;
	cout<<d[V-1]<<endl;
		rep(i,0,V)while(!G[i].empty())G[i].pop_back();
}
}