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;
#define rep(i,n) for(int i = 0; i < (n) ; i++)
constexpr auto INF = 2147483647;
typedef long long ll;

static const int UP = 0;
static const int LEFT = 1;
static const int DOWN = 2;
static const int RIGHT = 3;

int dh[4] = {-1,0,1,0};
int dw[4] = {0,-1,0,1};

int adjacent_graph[30][30][4];


int BFS(int h, int w){
  vector<vector<int>> color_graph(h,vector<int>(w));
  rep(i,h)rep(j,w) color_graph[i][j] = 0;
  queue<pair<int,int>> que;
  que.emplace(make_pair(0,0));
  color_graph[0][0] = 1;
  while(!que.empty()){
    pair<int,int> now  = que.front(); que.pop();
    rep(d,4){
      int n_h = now.first + dh[d];
      int n_w = now.second + dw[d];
      if(0 <= n_h && n_h < h && 0 <= n_w && n_w < w && adjacent_graph[now.first][now.second][d] == 0 && color_graph[n_h][n_w] == 0){
        color_graph[n_h][n_w] = color_graph[now.first][now.second] + 1;
        que.emplace(make_pair(n_h,n_w));
      }
    }
  }

  return color_graph[h-1][w-1];
}

int main(){
  // init
 int H, W, input;


  while(true){
    //input
    cin >> W >> H;
    if (H == 0)break;
    rep(i,H){
      adjacent_graph[i][0][LEFT] = 1;
      adjacent_graph[i][W-1][RIGHT] = 1;
    }
    rep(i,H){
      adjacent_graph[0][i][UP] = 1;
      adjacent_graph[H-1][i][DOWN] = 1;
    }
    rep(i,2*H-1){
      int tmp_H = i/2;
      int tmp_W;
      if(i%2 ==0) {
        tmp_W = W -1;
        rep(j,tmp_W){
          cin >> input;
          adjacent_graph[tmp_H][j][RIGHT] = input;
          adjacent_graph[tmp_H][j+1][LEFT] = input;
        }
      }
      else{
        tmp_W = W;
        rep(j,tmp_W){
          cin >> input;
          adjacent_graph[tmp_H][j][DOWN] = input;
          adjacent_graph[tmp_H+1][j][UP] = input;
        }
      }
    }
    //BFS
    int ans = BFS(H,W);
    cout << ans << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cmath>
#include <queue>
#include <utility>
#include <cstring>
using namespace std;

#define INF 1000
#define TEST 0
#if TEST
FILE* in = freopen("./B.txt", "r", stdin);
FILE* out = freopen("./ans.txt", "w", stdout);
#endif

int w, h;
int barrier[2][40][40];
int cost[40][40];

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

inline bool isRegion(int x, int y){
    return x >= 0 && x < w && y >= 0 && y < h;
}

void bfs(){
    bool isChecked[40][40] = {false};
    queue<pair<int,int> > q;
    q.push(make_pair(0,0));
    isChecked[0][0] = true;
    
    while(!q.empty()){
        int x = q.front().first;
        int y = q.front().second;
        q.pop();
        cost[x][y] = INF;
        if(!x && !y) cost[x][y] = 1;
        
        for(int i = 0; i < 4; i++){
            int nx = x + dx[i], ny = y + dy[i];
            
            int isV = (i+1) & 1;
            int minX = min(x, nx), minY = min(y, ny);
            if(isRegion(nx, ny) && !barrier[isV][minX][minY]){
                if(cost[nx][ny]){
                    cost[x][y] = min(cost[x][y], cost[nx][ny] + 1);
                } else if(!isChecked[nx][ny]){
                    q.push(make_pair(nx, ny));
                    isChecked[nx][ny] = true;
                }
            }
        }
    }
}

int main(int argc, const char * argv[]) {
    
    int cnt = 0;
    while(1){
        scanf("%d %d", &w, &h);
        if(!w && !h) break;
        cnt++;
        
        // ?????????
        memset(cost, 0, sizeof(cost));

        // ??\???
        for(int y = 0; y < h; y++){
            for(int x = 0; x < w - 1; x++){
                scanf("%d", &barrier[0][x][y]);
            }
            if(y != h-1){
                for(int x = 0; x < w; x++){
                    scanf("%d", &barrier[1][x][y]);
                }
            }
        }
        
        // ???????????¢?´¢
        bfs();
        //cout << cnt << "(w=" << w << ",h=" << h << "): ";
        cout << cost[w-1][h-1] << endl;
    }
#if TEST
    fclose(in);
    fclose(out);
#endif
}