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 <cassert>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <array>

using namespace std;

#define all(c) begin(c), end(c)
#define dump(c) cerr << "> " << #c << " = " << (c) << endl
#define REP(i, a, b) for (int i = (a); i < (int)(b); i++)
#define rep(i, n) REP(i, 0, n)

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;

const int INF = 1001001001;
const double EPS = 1e-10;


template<typename T1,typename T2>
ostream& operator<<(ostream& os, const pair<T1,T2>& p){
  return os << '(' << p.first <<',' << p.second << ')';
}
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& a){
  os << '[';
  rep(i,a.size()) os << (i ? " " : "") << a[i];
  return os << ']';
}

#define at(i, j) ((i) * W + (j))
int main() {
  for(int W, H; cin >> W >> H, (W | H) != 0; ) {
    vector<vector<pii>> adj(W * H * W * H);

    rep(i, 2 * H - 1) {
      if (!(i & 1)) {
        rep(j, W - 1) {
          int e; cin >> e;
          if (e) continue;
          adj[at(i / 2, j)].emplace_back(j + 1, i / 2);
          adj[at(i / 2, j + 1)].emplace_back(j, i / 2);
        }
      }
      else {
        rep(j, W) {
          int e; cin >> e;
          if (e) continue;
          adj[at(i / 2, j)].emplace_back(j, i / 2 + 1);
          adj[at(i / 2 + 1, j)].emplace_back(j, i / 2);
        }
      }
    }

    queue<pii> que;
    que.emplace(0, 0);
    int dist[30][30] = {};
    dist[0][0] = 1;
    while(!que.empty()) {
      int x, y;
      tie(x, y) = que.front();
      que.pop();

      for(auto p : adj[at(y, x)]) {
        int tx, ty;
        tie(tx, ty) = p;
        assert(abs(x - tx) + abs(y - ty) <= 1);
        if(dist[ty][tx]) continue;
        dist[ty][tx] = dist[y][x] + 1;
        que.emplace(tx, ty);
      }
    }

    cout << dist[H - 1][W - 1] << endl;
  }
  
  
  return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<queue>
#include<sstream>
using namespace std;

int w,h;
bool start(){
  string s;
  getline(cin,s);
  stringstream ss(s);
  ss>>w>>h;
  return w!=0&&h!=0;
}
typedef pair<int,int> pii;
#define X first
#define Y second
vector<string> f;
struct S{
  int c;
  pii p;
};
bool operator<(S a,S b){
  return a.c>b.c;
}
const int vx[]= {0,0,1,-1};
const int vy[]= {1,-1,0,0};
const bool check(int x,int y){
  return (0<=x)&&(x<f.size())&&(0<=y)&&(y<f[x].size());
}
int find(pii start,pii end){
  priority_queue<S> q;
  q.push(S{1,start});
  vector<vector<int>> dp(f.size(),vector<int>(f[0].size(),-1));
  while(!q.empty()){
    S now = q.top();q.pop();
    if(now.p == end){
      return now.c;
    }
    if(dp[now.p.X][now.p.Y]!=-1)continue;
    dp[now.p.X][now.p.Y]=now.c;
    for(int i=0;i<4;i++){
      const int x = now.p.X+vx[i];
      const int y = now.p.Y+vy[i];
      if(check(x,y)&&f[x][y]!='1'){
        q.push(S{now.c+(f[x][y]=='*'),pii(x,y)});
      }
    }
  }
  return -1;
}



int solve(){
  f.clear();f.resize(2*h-1);
  for(int i=0;i<f.size();i++){
    getline(cin,f[i]);
    if(i%2==0)f[i]=f[i]+=' ';
  }
  for(int i=0;i<f.size();i+=2){
    for(int j=0;j<f[i].size();j+=2){
      f[i][j]='*';
    }
  }
  for(int i=0;i<f.size();i++){
    for(int j=0;j<f[i].size();j++){
      if(f[i][j]==' '){
        f[i][j]='1';
      }
    }
  }
  return find(pii(0,0),pii(f.size()-1,f[0].size()-1));
}

int main(){
  while(start()){
    cout<<solve()<<endl;
  }
}