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 <queue>
using namespace std;

int w,h,ans;
int map[59][59];
int reached[59][59];
queue<int> nx,ny,cnt;

void search(int cnt,int x,int y){
  if(cnt>=ans||reached[y][x]) return;
  if(x==2*(w-1)&&y==2*(h-1)){
    if(cnt<ans) ans=cnt;
    return;
  }
  reached[y][x]=1;
  if(x<2*(w-1)&&map[y][x+1]==0) search(cnt+1,x+2,y);
  if(y<2*(h-1)&&map[y+1][x]==0) search(cnt+1,x,y+2);
  if(x>0&&map[y][x-1]==0) search(cnt+1,x-2,y);
  if(y>0&&map[y-1][x]==0) search(cnt+1,x,y-2);
  reached[y][x]=0;
}

void v_search(){
  nx.push(0); ny.push(0); cnt.push(1);
  while(!nx.empty()&&!ny.empty()){
    int x=nx.front(); int y=ny.front(); int c=cnt.front();
    nx.pop(); ny.pop(); cnt.pop();
    if(c>=ans||reached[y][x]) continue;
    if(x==2*(w-1)&&y==2*(h-1)&&c<ans){
      ans=c; continue;
    }
    reached[y][x]=1;
    if(x<2*(w-1)&&map[y][x+1]==0&&reached[y][x+1]==0){
      nx.push(x+2); ny.push(y); cnt.push(c+1);
    }
    if(y<2*(h-1)&&map[y+1][x]==0&&reached[y+1][x]==0){
      nx.push(x); ny.push(y+2); cnt.push(c+1);
    }
    if(x>0&&map[y][x-1]==0&&reached[y][x-1]==0){
      nx.push(x-2); ny.push(y); cnt.push(c+1);
    }
    if(y>0&&map[y-1][x]==0&&reached[y-1][x]==0){
      nx.push(x); ny.push(y-2); cnt.push(c+1);
    }
  }
}

int main(){
  while(cin>>w>>h,w){
    for(int i=0;i<h*2-1;i++){
      if(i%2==0){
	for(int j=0;j<w*2-1;j++){
	  if(j%2==0) map[i][j]=reached[i][j]=0;
	  else cin>>map[i][j];
	}
      } else{
	for(int j=0;j<w*2-1;j++){
	  if(j%2==0) cin>>map[i][j];
	  else map[i][j]=reached[i][j]=0;
	}
      }
    }
    /*for(int i=0;i<h*2-1;i++){
      for(int j=0;j<w*2-1;j++)
	cout<<map[i][j]<<" ";
      cout<<endl;
      }*/
    ans=10000;
    v_search();
    if(ans==10000) ans=0;
    cout<<ans<<endl;
  }
}

C++: #include "bits/stdc++.h"
using namespace std;

const int INF = 1000000;
int dx[4] = { 1, 0, -1, 0 }, dy[4] = { 0, 1, 0, -1 };

int main() {
	int W, H;
	while (cin >> W >> H) {
		if (W == 0) return 0;
		H = H * 2 - 1, W = W * 2 - 1;
		vector<vector<int> > V(H, vector<int>(W));
		for (int i = 0; i < H; i++) {
			for (int j = 0; j < W; j++) {
				if (i % 2 == j % 2) V[i][j] = i % 2;
				else cin >> V[i][j];
			}
		}
		vector<vector<int> > Dist(H, vector<int>(W, INF));
		queue<pair<int, int> > Q;
		Q.push({ 0, 0 });
		Dist[0][0] = 0;
		while (!Q.empty()) {
			pair<int, int> P = Q.front();
			Q.pop();
			int X = P.first, Y = P.second;
			for (int i = 0; i < 4; i++) {
				int NX = X + dx[i], NY = Y + dy[i];
				if (0 <= NX && NX < H && 0 <= NY && NY < W) {
					if (V[NX][NY] == 0 && Dist[NX][NY] > Dist[X][Y] + 1) {
						Dist[NX][NY] = Dist[X][Y] + 1;
						Q.push({ NX, NY });
					}
				}
			}
		}
		cout << (Dist[H - 1][W - 1] == INF ? 0 : Dist[H - 1][W - 1] / 2 + 1) << endl;
	}
}

C++: #include <iostream>
#include <queue>
#include <map>
using namespace std;
int main(){
  int x,y;
  bool f;
  while(cin >>x>>y, x|y){
    int field[30][30][2] = {0};
    for(int i=0; i<y-1; i++){
      for(int k=0; k<x-1; k++){
	cin >>f;
	if(f){
	  field[k][i][1]|=1<<2;
	  field[k+1][i][1]|=1<<4;
	}
      }
      for(int k=0; k<x; k++){
	cin >>f;
	if(f){
	  field[k][i][1]|=1<<3;
	  field[k][i+1][1]|=1<<1;
	}
      }
    }
    for(int i=0; i<x-1; i++){
      cin >>f;
      if(f){
	field[i][y-1][1]|=1<<2;
	field[i+1][y-1][1]|=1<<4;
      }
    }
    field[0][0][0] = 1;
    queue<pair<int ,int> > q;
    q.push(make_pair(0,0));
    while(!q.empty()){
      int px = q.front().first, py = q.front().second, now = field[px][py][0];
      if(!(field[px][py][1] & 1<<1) && py>0){if(!field[px][py-1][0]){field[px][py-1][0] = now+1;q.push(make_pair(px,py-1));}}
      if(!(field[px][py][1] & 1<<2) && px<x-1){if(!field[px+1][py][0]){field[px+1][py][0] = now+1;q.push(make_pair(px+1,py));}}
      if(!(field[px][py][1] & 1<<3) && py<y-1){if(!field[px][py+1][0]){field[px][py+1][0] = now+1;q.push(make_pair(px,py+1));}}
      if(!(field[px][py][1] & 1<<4) && px>0){if(!field[px-1][py][0]){field[px-1][py][0] = now+1;q.push(make_pair(px-1,py));}}
      q.pop();
    }
    cout <<field[x-1][y-1][0]<<endl;
  }
  return 0;
}