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 <bits/stdc++.h>

using namespace std;

typedef pair<int, int> P;

int maze[60][60];
int dist[60][60];

int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};

int bfs(int w, int h)
{
  queue<P> que;
  memset(dist, -1, sizeof(dist));
  que.push(P(0, 0));
  dist[0][0] = 1;
  while(!que.empty()){
    P p = que.front(); que.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(nx < 0 || w <= nx || ny < 0 || h <= ny) continue;
      if(maze[ny][nx] == 1 || dist[ny][nx] != -1) continue;
      que.push(P(nx, ny));
      dist[ny][nx] = dist[y][x] + 1;
    }
  }
  return dist[h-1][w-1];
}

int main()
{
  int w, h;
  while(cin >> w >> h, w || h){
    w = 2*w - 1;
    h = 2*h - 1;
    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++){
	if(i % 2 == 1 || j % 2 == 1) maze[i][j] = 1;
	else maze[i][j] = 0;
      }
    }
    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++){
	if(i % 2 == 0 && j % 2 == 0) continue;
	if(i % 2 == 1 && j % 2 == 1) continue;
	cin >> maze[i][j];
      }
    }
    cout << (bfs(w, h) + 1) / 2 << endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define REP(i,n) for (int i=0;i<(n);i++)
#define ALL(a) (a).begin(),(a).end()
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define ll long long
#define ull unsigned long long
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

using namespace std;

int main(){
  int w,h;
  vector<vector<int>> mp;
  while(cin >> w >> h){
    if(!w)break;
    mp.resize(2*h-1,vector<int>(2*w-1,0));
    int W = 2*w-1;
    int H = 2*h-1;
    for(int i=0;i<H-2;i+=2){
	for(int j=0;j<W-2;j+=2){
	cin >> mp[i][j+1];
      }
      for(int j=0;j<W;j+=2){
	cin >> mp[i+1][j];
      }
    }
    for(int j=0;j<W-2;j+=2){
      cin >> mp[H-1][j+1];
    }
    /*    REP(i,H){
      REP(j,W)cout << mp[i][j] << " ";
      cout << endl;
      }*/
    queue<pair<int,int>> que;
    que.push(make_pair(0,0));
    mp[0][0] = 1;
    while(que.size()){
      pair<int,int> p = que.front();
      que.pop();
      for(int k=0;k<4;k++){
	int y = p.first+2*dy[k];
	int x = p.second+2*dx[k];
	if(x>=0 && x<W && y>=0 && y<H){
	  if(mp[p.first+dy[k]][p.second+dx[k]])continue;
	  if(mp[p.first][p.second]+1 > mp[y][x] && mp[y][x]>0)
	    continue;
	  else{
	    mp[y][x] = mp[p.first][p.second]+1;
	    que.push(make_pair(y,x));
	  }
	}
      }
    }
    cout << mp[H-1][W-1] << endl;
    mp.clear();
  }
    return 0;
}