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<stdio.h>
#include<iostream>
#include<math.h>
#include<algorithm>
#include<string>
#include<utility>
#include<queue>
#define pi 3.14159
#define Inf (int)pow(2., 20.)

using namespace std;
typedef std::pair<int, int> mypair;
int w, h, a[59][59];
queue<mypair> qu;
void bfs(int y, int x);

int main(){
	while(1) {
		cin >> w >> h;
		if(w == 0 && h == 0) break;
		for(int i = 0; i < 2*h-1; i++) {
			for(int j = 0; j < 2*w-1; j++) {
				if(i % 2 == 0 && j % 2 == 0) a[i][j] = Inf;
				else if(i % 2 == 1 && j % 2 == 1) a[i][j] = Inf;
				else cin >> a[i][j];
			}
		}
		a[0][0] = 1;
		if(a[0][1] == 0) {
			qu.push(mypair(0, 2));
			a[0][2] = 2;
		}
		if(a[1][0] == 0) {
			qu.push(mypair(2, 0));
			a[2][0] = 2;
		}
		bfs(qu.front().first, qu.front().second);
		if(a[2*h-2][2*w-2] == Inf) cout << 0 <<endl;
		else cout << a[2*h-2][2*w-2] <<endl;
		for(int i = 0; i*2 < 2*h-1; i++) {
			for(int j = 0; j*2 < 2*w-1; j++) {
				cout << a[i*2][j*2] << " " ;
			}
			cout << endl;
		}
	}
	return 0;
}

void bfs(int y, int x) {
	qu.pop();
	
	if(y == 2*h-2 && x == 2*w-2) return;
	if(x + 1 < 2*w-1) {
		if(a[y][x+1] == 0 && a[y][x+2] > a[y][x] + 1) {
			qu.push(mypair(y, x+2));
			a[y][x+2] = a[y][x] + 1;
		}
	}
	if(y+1 < 2*h-1) { 
		if(a[y+1][x] == 0 && a[y+2][x] > a[y][x] + 1) {
			qu.push(mypair(y+2, x));
			a[y+2][x] = a[y][x] + 1;
		}
	}
	if(y - 1 >= 0) {
		if(a[y-1][x] == 0 && a[y-2][x] > a[y][x] + 1) {
			qu.push(mypair(y-2, x));
			a[y-2][x] = a[y][x] +1;
		}
	}
	if(x - 1 >= 0) {
		if(a[y][x-1] == 0 && a[y][x-2] > a[y][x] + 1) {
			qu.push(mypair(y, x-2));
			a[y][x-2] = a[y][x] + 1;
		}
	}
	if(qu.empty() == false) bfs(qu.front().first, qu.front().second);
	return;
}

C++: #include <iostream>
#include <vector>
#include <queue>
using namespace std;

int main()
{
  int W, H;
  while (cin >> W >> H && W != 0) {
    vector<vector<int> > grid(2*H+1, vector<int>(2*W+1, 0));
    for (int i = 0; i < 2*H+1; i++) {
      grid[i][0] = grid[i][2*W] = 1;
    }
    for (int j = 0; j < 2*W+1; j++) {
      grid[0][j] = grid[2*H][j] = 1;
    }
    grid[0][1] = 0;
    grid[2*H][2*W-1] = 0;

    for (int j = 1; j < W; j++) {
      cin >> grid[1][2*j];
      if (grid[1][2*j]) {
        grid[2][2*j] = 1;
      }
    }
    for (int i = 1; i < H; i++) {
      for (int j = 0; j < W; j++) {
        cin >> grid[2*i][2*j+1];
        if (grid[2*i][2*j+1]) {
          grid[2*i][2*j] = grid[2*i][2*j+2] = 1;
        }
      }
      for (int j = 1; j < W; j++) {
        cin >> grid[2*i+1][2*j];
        if (grid[2*i+1][2*j]) {
          grid[2*i][2*j] = grid[2*i+2][2*j] = 1;
        }
      }
    }

    queue<pair<int,int> > q;
    q.push(make_pair(0, 1));
    vector<vector<int> > dist(2*H+1, vector<int>(2*W+1, 1000000));
    dist[0][1] = 0;
    const pair<int,int> goal(2*H, 2*W-1);
    while (!q.empty()) {
      const pair<int,int> p = q.front();
      q.pop();
      const int c = dist[p.first][p.second];
      if (p == goal) {
        cout << c/2 << endl;
        goto NEXT;
      }
      for (int d = 0; d < 4; d++) {
        static const int di[] = {-1, 1, 0, 0};
        static const int dj[] = {0, 0, -1, 1};
        const int i = p.first + di[d];
        const int j = p.second + dj[d];
        if (i >= 0 && j >= 0 && !grid[i][j] && c+1 < dist[i][j]) {
          dist[i][j] = c+1;
          q.push(make_pair(i, j));
        }
      }
    }
    cout << 0 << endl;
NEXT:
    ;
  }
  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>,vector<pair<int,int>>,greater<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;
}