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;

int W, H;
int field[50][50][4];
int len[50][50];
int dx[] = {1, 0, -1, 0};
int dy[] = {0, -1, 0, 1};
int INF = 100000;
int main(){
	while(cin >> W >> H, W && H){
		for(int i = 0; i < H; i++){
			for(int j = 0; j < W; j++){
				len[i][j] = INF;
				for(int k = 0; k < 4; k++){
					field[i][j][k] = 0;
				}
			}
		}
		int val;
		for(int i = 0; i < H; i++){
			for(int j = 0; j < W - 1; j++){
				cin >> val;
				if(!val){
					field[i][j][0]     = 1;
					field[i][j + 1][2] = 1;
				}
			}
			if(i == H - 1) break;
			for(int j = 0; j < W; j++){
				cin >> val;
				if(!val){
					field[i][j][3]     = 1;
					field[i + 1][j][1] = 1;
				}
			}
		}
		queue<pair<int, int> > qu;
		qu.push(make_pair(0, 0));
		len[0][0] = 1;
		while(!qu.empty()){
			pair<int, int> p = qu.front();
			qu.pop();
			for(int i = 0; i < 4; i++){
				if(field[p.first][p.second][i]){
					int nx = p.second + dx[i];
					int ny = p.first + dy[i];
					if(len[ny][nx] == INF){
						len[ny][nx] = len[p.first][p.second] + 1;
						qu.push(make_pair(ny, nx));
					}
				}
			}
		}
		cout << (len[H - 1][W - 1] == INF ? 0 : len[H - 1][W - 1]) << endl;
	}
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstring>
#include <cctype>
#include <cmath>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <list>
#include <stdio.h>
#include <string.h>
#include <cstdlib>
#include <math.h>
#include <bitset>
#include <iterator>
#include <iomanip>
#include <sstream>
#define INF 2000000000
using namespace std;
int dx[4]={0,1,0,-1},dy[4]={-1,0,1,0};
#define ll long long
#define PL pair<long long, long long>
#define P pair<int,int>
#define mk make_pair
#define en endl
#define WHITE 0
#define BLACK 2
#define GRAY 1
#define RE return 0
#define int ll

int done[33][33];

signed main(){
  int w,h;
  while(cin>>w>>h&&w&&h){
    bool wall[35][35][5];
    for(int i=0; i<33; i++) for(int j=0; j<33; j++) for(int k=0; k<=4; k++) {wall[i][j][k]=false; done[i][j]=INF;}
    
    for(int i=1; i<=2*h-1; i++){
      int tate=(i+1)/2;
      if(i%2){
        for(int j=1; j<w; j++){
          int a;
          cin>>a;
          if(a==1){
            wall[tate][j][1]=true;
            wall[tate][j+1][3]=true;
          }
        }
      }else{
        for(int j=1; j<=w; j++){
          int a;
          cin>>a;
          if(a==1){
            wall[tate][j][2]=true;
            wall[tate+1][j][0]=true;
          }
        }
      }
    }
    
    
    queue<P> que;
    que.push(mk(1,1));
    done[1][1]=1;
    
    int fast=INF;
    while(!que.empty()){
      int y=que.front().first,x=que.front().second;
      if(y==h&&x==w){
        fast=min(fast,done[y][x]);
      }
      que.pop();
      for(int k=0; k<4; k++){
        int new_y=y+dy[k],new_x=x+dx[k];
        if(wall[y][x][k]==false && new_x>=1 && new_y<=h && new_y>=1 && new_x<=w && done[new_y][new_x]==INF){
          done[new_y][new_x]=done[y][x]+1;
          que.push(mk(new_y,new_x));
        }
      }
    }
    
    
    if(fast==INF){
      cout<<0<<en;
    }else{
      cout<<fast<<en;
    }
  }
}

C++: #include <iostream>
#include <queue>

using namespace std;

int main()
{
	for(int w,h;cin>>w>>h,w|h;){
		cin.ignore();
		vector<string> grid(h*2-1);
		for(int i=0;i<h*2-1;i++)
			getline(cin,grid[i]);
		
		for(int i=0;i<grid.size();i++){
			if(!(i&1))
				grid[i]+=' ';
			for(int j=0;j<grid[i].size();j++){
				if((i&j)&1)
					grid[i][j]='1';
				if((~i&~j)&1)
					grid[i][j]='0';
			}
		}
		
		vector<vector<int> > vis(grid.size(),vector<int>(grid[0].size()));
		queue<pair<int,int> > q;
		q.push(make_pair(0,0));
		vis[0][0]=1;
		while(q.size()){
			pair<int,int> cur=q.front(); q.pop();
			int di[]={-1,1,0,0},dj[]={0,0,-1,1};
			for(int k=0;k<4;k++){
				int ni=cur.first+di[k],nj=cur.second+dj[k];
				if(ni<0 || grid.size()<=ni || nj<0 || grid[0].size()<=nj)
					continue;
				if(grid[ni][nj]=='1' || vis[ni][nj])
					continue;
				vis[ni][nj]=vis[cur.first][cur.second]+1;
				q.push(make_pair(ni,nj));
			}
		}
		
		int res=(vis.back().back()+1)/2;
		cout<<res<<endl;
	}
	
	return 0;
}