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 <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>

using namespace std;

using ll = long long;

#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define REPD(i,n) for(ll i=n-1;i>=0;i--)
#define FOR(i,a,b) for(ll i=a;i<=(ll)(b);i++)
#define FORD(i,a,b) for(ll i=a;i>=(ll)(b);i--)

#define input(...) __VA_ARGS__; in(__VA_ARGS__)

template<class T>
void print(vector<T> a) {
  cout << "[ ";
  REP(i, a.size()) cout << a[i] << " ";
  cout << "]" << endl;
}

void print() {
  std::cout << std::endl;
}

template <class Head, class... Tail>
void print(Head&& head, Tail&&... tail) {
  std::cout << head << " ";
  print(std::forward<Tail>(tail)...);
}

void in() { }

template <class Head, class... Tail>
void in(Head&& head, Tail&&... tail) {
  cin >> head;
  in(std::forward<Tail>(tail)...);
}

vector<pair<ll, ll>> directions = {
  {+0, +2},
  {+0, -2},
  {+2, +0},
  {-2, +0},
};

struct Value {
  ll y, x, cost;
};
Value bfs(ll sy, ll sx, vector<vector<ll>> &grid) {

  queue<Value> que;
  que.push({sy, sx, 0});

  while (!que.empty()) {
    Value node = que.front();
    que.pop();

    // --- 終端 ---
    if (node.y == grid.size() - 2 && node.x == grid[0].size() - 2) {
      return node;
    }

    if (grid[node.y][node.x] != 0) continue;
    grid[node.y][node.x] = 8;

    for(auto d: directions) {
      ll ny = node.y + d.first, nx = node.x + d.second;
      if (0 <= ny && ny < grid.size() && 0 <= nx && nx < grid[ny].size()
          && grid[ny][nx] == 0 && grid[node.y + d.first / 2][node.x + d.second / 2] == 0) {
        que.push({ny, nx, node.cost + 1});
      }
    }
  }
  return {-1, -1, -1};
}

bool solve() {
  ll input(w, h);
  if (w == 0 && h == 0) return false;

  vector<vector<ll>> grid(h * 2, vector<ll>(w * 2));
  REP(i, h * 2 - 1) {
    if (i % 2 == 0) {
      REP(j, w - 1) {
        cin >> grid[i][j * 2 + 1];
      }
    } else {
      REP(j, w) {
        cin >> grid[i][j * 2];
      }
    }
  }

  // for(auto v: grid) print(v);
  // print("---");
  cout << bfs(0, 0, grid).cost + 1 << endl;
  // for(auto v: grid) print(v);
  return true;
}

int main() {
  while(solve());
}

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];
		for(int i=0;i<31*30;i++) passed[i]=false;
		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;
}