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 <vector>
#include <queue>
using namespace std;

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

int main(void){
  while(true){
    int w, h;
    cin >> w >> h;
    if(w == 0 && h == 0){ break; }

    vector<vector<vector<bool> > > canGo(h + 2, vector<vector<bool> >(w + 2, vector<bool>(4, true)));
    for(int i = 0; i < h + 2; i++)
      for(int j = 0; j < w + 2; j++)
        for(int k = 0; k < 4; k++)
          if(i + dx[k] <= 0 || i + dx[k] > h || j + dy[k] <= 0 || j + dy[k] > w)
            canGo[i][j][k] = false;

    int input;
    for(int i = 0; i < 2 * h - 1; i++){
      if(i % 2 == 0){
        for(int j = 1; j <= w - 1; j++){
          cin >> input;
          if(input == 1){
            canGo[i / 2 + 1][j][3] = false;
            canGo[i / 2 + 1][j + 1][1] = false; 
          }
        } 
      }
      else{
        for(int j = 1; j <= w; j++){
          cin >> input;
          if(input == 1){
            canGo[i / 2 + 1][j][2] = false;
            canGo[i / 2 + 2][j][0] = false; 
          }
        }
      }
    }

    queue<pair<int, pair<int, int> > > wait;
    wait.push(make_pair(0, make_pair(1, 1)));
    for(int i = 0; i < 4; i++)
      canGo[1 + dx[i]][1 + dy[i]][(i + 2) % 4] = false;

    int ans = -1;
    while(!wait.empty()){
      int cost = wait.front().first;
      int x = wait.front().second.first;
      int y = wait.front().second.second;
      wait.pop();
      if(x == h && y == w){
        ans = cost;
        break;
      }

      for(int i = 0; i < 4; i++){
        if(canGo[x][y][i]){
          int nextX = x + dx[i];
          int nextY = y + dy[i];
          wait.push(make_pair(cost + 1, make_pair(nextX, nextY)));
          for(int j = 0; j < 4; j++)
            canGo[nextX + dx[j]][nextY + dy[j]][(j + 2) % 4] = false;
        }
      }
    }

    cout << ans + 1 << endl;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
#define at(x,y) (x)*30+y
using namespace std;

int main(){
	int w,h;
	while(cin >> w >> h,w||h){
		vector<vector<int>> v(w*31);
		for(int i=0;i<2*h-1;i++){
			for(int j=0;j<w-((i+1)%2);j++){
				int c;
				cin >> c;
				if(c) continue;
				if(i%2){//???
					v[at(j,i/2)].emplace_back(at(j,i/2+1));
					v[at(j,i/2+1)].emplace_back(at(j,i/2));
				} else{//?¨?
					v[at(j,i/2)].emplace_back(at(j+1,i/2));
					v[at(j+1,i/2)].emplace_back(at(j,i/2));
				}
			}
		}
		priority_queue<pair<int,int>> pq;
		pq.push(make_pair(1,at(0,0)));
		bool passed[31*30] = {0};
		int ans = 0;
		while(!pq.empty()){
			pair<int,int> x = pq.top();
			pq.pop();
			if(x.second == at(w-1,h-1)){
				ans = x.first;
				break;
			}
			
			if(passed[x.second]) continue;
			passed[x.second] = true;
			for(int unsigned i = 0;i<v[x.second].size();i++){
				pq.push(make_pair(x.first+1,v[x.second][i]));
			}
		}
		cout << ans << endl;
	}
	return 0;
}

C++: #include<bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define reps(i,s,n) for(int i=(int)(s);i<(int)(n);i++)
const ll mod = ll(1e9) + 7;
const int INF = int(1e9);

int w, h;
int ww[30][30], wh[30][30];
bool m[30][30];
int solve() {
	queue <pair<pair<int, int>, int>>que;
	que.push({ {0,0},1 });
	while (que.size()) {
		int x = que.front().first.first;
		int y = que.front().first.second;
		int cnt = que.front().second;
		//cout << x << " " << y << endl;
		que.pop();
		if (x == w - 1 && y == h - 1)return cnt;
		if (x != 0) {
			if (wh[x - 1][y] != 1&&m[x-1][y]!=1) {
				que.push({ {x - 1,y},cnt + 1 });
				m[x - 1][y] = 1;
			}
		}
		if (x != w - 1) {
			if (wh[x][y] != 1 && m[x+1][y] != 1) {
				que.push({ {x + 1,y},cnt + 1 });
				m[x + 1][y] = 1;
			}
		}
		if (y != 0) {
			if (ww[x][y - 1] != 1 && m[x][y - 1] != 1) {
				que.push({ {x,y - 1},cnt + 1 });
				m[x][y - 1] = 1;
			}
		}
		if (y != h - 1) {
			if (ww[x][y] != 1 && m[x][y + 1] != 1) {
				que.push({ {x,y + 1},cnt + 1 });
				m[x][y + 1] = 1;
			}
		}
	}
	return 0;
}

int main() {
	cin.sync_with_stdio(false);
	while (1) {
		cin >> w >> h;
		if (w == 0)return 0;
		ww[30][30] = {}, wh[30][30] = {};
		int cnth = 0;
		while (cnth < h) {
			rep(i, w-1) cin >> wh[i][cnth];
			if (cnth + 1 < h) {
				rep(i, w)cin >> ww[i][cnth];
			}
			cnth++;
		}
		m[30][30] = {};
		cout << solve() << endl;

	}

	return 0;
}