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 <algorithm>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stdlib.h>
#include <string>
#include <utility>
#include <vector>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define loop(i, x, n) for (int i = (x); i < (n); i++)
#define all(v) (v).begin(), (v).end()
//#define int long long
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 1e8;
template<typename T> void cmax(T &a, T b) { a = max(a, b); }
template<typename T> void cmin(T &a, T b) { a = min(a, b); }
int dy[4] = {-1, 0, 1, 0};
int dx[4] = {0, 1, 0, -1};

int main() {
  int w, h;
  while (cin >> w >> h) {
    if (h == 0 && w == 0) break;
    bool mp[50][50][4] = {};
    rep(i, 2 * h - 1) {
      int x;
      if (i % 2 == 0) {
        rep(j, w - 1) {
          cin >> x;
          if (x == 1) {
            mp[i / 2][j][1] = 1;
            mp[i / 2][j + 1][3] = 1;
          }
        }
      } else {
        rep(j, w) {
          cin >> x;
          if (x == 1) {
            mp[i / 2][j][2] = 1;
            mp[i / 2 + 1][j][0] = 1;
          }
        }
      }
    }
    // rep(i, h) {
    //   rep(j, w) { rep(k, 4) cout << mp[i][j][k] << ' '; }
    //   cout << endl;
    //   cout << endl;
    // }

    int ans[50][50];
    bool used[50][50] = {};
    rep(i, 50) rep(j, 50) ans[i][j] = INF;
    ans[0][0] = 0;
    queue<pair<int, int>> q;
    q.push({0, 0});
    while (!q.empty()) {
      pair<int, int> p = q.front();
      q.pop();
      int y = p.first;
      int x = p.second;
      if (used[y][x]) continue;
      used[y][x] = 1;

      if (y == h - 1 && x == w - 1) break;
      rep(i, 4) {
        int ny = y + dy[i];
        int nx = x + dx[i];
        if (0 <= nx && nx < w && 0 <= ny && ny < h && mp[y][x][i] == 0 && used[ny][nx] == 0) {
          cmin(ans[ny][nx], ans[y][x] + 1);
          q.push({ny, nx});
        }
      }
    }
    // cout << endl;
    // rep(i, h) {
    //   rep(j, w) { cout << ans[i][j] << ' '; }
    //   cout << endl;
    // }
    cout << (ans[h - 1][w - 1] == INF ? 0 : ans[h - 1][w - 1] + 1) << endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define INF -1
typedef pair<int,int> P;
#define MAX_H 59
#define MAX_W 59
char maze[MAX_H][MAX_W+1];
int h,w;
int sx,sy;
int gx,gy;
int dp[MAX_H][MAX_W];
const int dx[4]={1,0,-1,0};
const int dy[4]={0,-1,0,1};
int main(){
    while(scanf("%d%d%*c",&w,&h)){
        int i,j;
        sx=0;
        sy=0;
        gx=2*h-2;
        gy=2*w-2;
        queue<P>que;
        P p;
        if(w==0 && h==0){
            break;
        }
        for(i=0;i<2*h-1;i++){
            for(j=0;j<2*w-2;j++){
                maze[i][j]=getchar();
            }
            if(i%2==0){
                maze[i][j]=' ';
            }else{
                maze[i][j]=getchar();
            }
            getchar();
        }
        for(i=0;i<2*h-1;i++){
            for(j=0;j<2*w-1;j++){
                dp[i][j]=INF;
            }
        }
        que.push(P(sx,sy));
        dp[sx][sy]=1;
        while(que.size()){
            p=que.front();
            que.pop();
            if(p.first==gx && p.second==gy){
                break;
            }
            for(i=0;i<4;i++){
                int nx=p.first+2*dx[i];
                int ny=p.second+2*dy[i];
                if(0<=nx && nx<(2*h-1) && 0<=ny && ny <(2*w-1) && maze[p.first+dx[i]][p.second+dy[i]]== '0' && dp[nx][ny]==INF){
                    que.push(P(nx,ny));
                    dp[nx][ny]=dp[p.first][p.second]+1;
                }
            }
        }
        for(j=0;j<2*h-1;j++){
            for(i=0;i<2*w-1;i++){
                printf("%2d",dp[i][j]);
            }
            printf("\n");
        }
        while(que.size()){
            que.pop();
        }
        if(dp[gx][gy]==INF){
            cout<<0<<endl;
        }else{
            cout<<dp[gx][gy]<<endl;
        }   
    }  
    return 0;
}