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 <cstdlib>
#include <cassert>
#include <algorithm>
#include <iostream>
#include <vector>
#include <queue>
using namespace std;

#define LET(name, value) __typeof(value) name = value
#define REP(i, n) for (int i = 0; i < (int)(n); ++i)
#define FOR(i, a, b) for (int i = (a); i < (int)(b); ++i)
#define FOREQ(i, a, b) for (int i = (a); i <= (int)(b); ++i)
#define ALL(c) (c).begin(), (c).end()
#define FOREACH(i, c) for (LET(i, (c).begin()); i != (c).end(); ++i)

vector<int> adj[910];
int cost[910];

inline void add_edge(int s, int t) {
  adj[s].push_back(t);
  adj[t].push_back(s);
}

int main() {
  int w, h;
  while (scanf("%d%d", &w, &h), w|h) {
    REP(i, w*h) { adj[i].clear(); }
    memset(cost, 0, sizeof(cost));

    REP(y, 2*h-1) {
      REP(x, w+y%2-1) {
        int d; scanf("%d", &d);
        if (d == 0) {
          if (y%2 == 0) {
            add_edge((y/2)*w+x, (y/2)*w+x+1);
          } else {
            add_edge((y/2)*w+x, (y/2+1)*w+x);
          }
        }
      }
    }

    queue<int> Q;
    cost[0] = 1;
    Q.push(0);
    while (!Q.empty()) {
      int v = Q.front(); Q.pop();
      if (v == w*h-1) { break; }
      FOREACH(it, adj[v]) {
        int u = *it;
        if (cost[u] == 0) {
          cost[u] = cost[v]+1;
          Q.push(u);
        }
      }
    }

    printf("%d\n", cost[w*h-1]);
  }
}

C++: #include<iostream>
#include<utility>
#define loop(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) loop(i,0,a)
#define INF 1e7
using namespace std;
typedef pair<int,int> pii;

int h,w;
bool edge[900][900];
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
bool check[31][31];
int dp[31][31];

bool out(int x,int y){
	if(x<0 || w<=x || y<0 || h<=y)return true;
	return false;
}

int syschange(pii a){
	return a.first+a.second*w;
}

bool wall(pii pre,pii now){
	if(edge[syschange(pre)][syschange(now)])return true;
	else return false;
}

void connect(pii pre,pii to){
	edge[syschange(pre)][syschange(to)]=edge[syschange(to)][syschange(pre)]=true;
}

int func(int x,int y){
	if(dp[x][y]!=INF)return dp[x][y];
	if(x==0 && y==0)return 1;
	int res=INF;
	rep(i,4){
		if(check[x-dx[i]][y-dy[i]])continue;
		if(out(x-dx[i],y-dy[i])){
			continue;
		}
		if(wall(pii(x-dx[i],y-dy[i]),pii(x,y))){
			continue;
		}
		check[x-dx[i]][y-dy[i]]=true;
		res=min(res,func(x-dx[i],y-dy[i])+1);
		check[x-dx[i]][y-dy[i]]=false;
	}
	return dp[x][y]=res;
}

int main(){
	int in;
	while(cin>>w>>h,w||h){
		rep(i,31)rep(j,31){
			check[i][j]=false;
			dp[i][j]=INF;
		}
		rep(i,900)rep(j,900)edge[i][j]=false;
		check[w-1][h-1]=true;
		rep(i,2*h-1){
			if(i%2){
				rep(j,w){
					cin>>in;
					if(in==1){
						pii pre=pii(j,i/2),to=pii(j,i/2+1);
						connect(pre,to);
					}
				}
			}else{
				rep(j,w-1){
					cin>>in;
					if(in==1){
						pii pre=pii(j,i/2),to=pii(j+1,i/2);
						connect(pre,to);
					}
				}
			}
		}
		int ans=func(w-1,h-1);
		cout<<((ans==INF)?0:ans)<<endl;
	}
	return 0;
}