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 <sstream>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <algorithm>
using namespace std;

#define NMAX 31
typedef pair <int, int> PII;
typedef pair <int, PII> PIP;

bool P[NMAX][NMAX][NMAX][NMAX];
int w, h;

bool isValid( PII p )
{
    int x = p.second;
    int y = p.first;
    return ( x >= 0 && x < w ) && ( y >= 0 && y < h );
}

bool isGoal( PII p )
{
    return p.first == h-1 && p.second == w-1;
}

int main( void )
{
    while ( cin >> w >> h && w && h )
    {
        // input
        int np;
        memset( P, false, sizeof( P ) );
        for ( int i = 0; i + 1 < 2 * h; i++ )
        {
            for ( int j = 0; j < ( i % 2 == 0 ? w - 1 : w ); j++ )
            {
                cin >> np;
                if ( !np )
                {
                    if ( i % 2 == 0 )
                    {
                        P[i/2][j][i/2][j+1] = P[i/2][j+1][i/2][j] = true;
                    }
                    else
                    {
                        P[i/2+1][j][i/2][j] = P[i/2][j][i/2+1][j] = true;
                    }
                }
            }
        }

        int answer = 0;
        set <PII> V;
        queue <PIP> Q;
        PIP s( 0, PII( 0, 0 ) );
        int dx[4] = { 0, 0, 1, -1 };
        int dy[4] = { 1, -1, 0, 0 };
        Q.push( s );
        V.insert( s.second );
        while ( !Q.empty() )
        {
            PIP e = Q.front();
            Q.pop();

            if ( isGoal( e.second ) )
            {
                answer = e.first + 1;
                break;
            }

            int t = e.first + 1;
            for ( int i = 0; i < 4; i++ )
            {
                PII pos = e.second;
                pos.first += dy[i];
                pos.second += dx[i];
                if ( !isValid( pos ) ) continue;
                if ( !P[e.second.first][e.second.second][pos.first][pos.second] ) continue;
                PIP next( t, pos );
                if ( V.find( pos ) != V.end() ) continue;
                Q.push( next );
                V.insert( pos );
            }
        }

        cout << answer << endl;
    }
    return 0;
}

C++: #include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
#include <string.h>
#define INF 10000
using namespace std;
int maze[33][33];
int d[33][33];
int w,h;
void solve(int i,int j,int c){
  if(i<0||i>=h) return;
  else if(j<0||j>=w) return;
  if(d[i][j]<=c) return;
  d[i][j]=c;
  //cout<<i<<","<<j<<":"<<c<<endl;
  if(!(maze[i][j]&1)) solve(i-1,j,c+1);
  if(!((maze[i][j]>>1)&1)) solve(i,j-1,c+1);
  if(!((maze[i][j]>>2)&1)) solve(i+1,j,c+1);
  if(!((maze[i][j]>>3)&1)) solve(i,j+1,c+1);
  return;
}
int main(void){
  int i,j;
  int res;
  string s;
  while(cin>>w>>h,w|h){
    getline(cin,s);
    for(i=0;i<h;i++){
      for(j=0;j<w;j++){
        maze[i][j]=0;
        d[i][j]=INF;
      }
    }
    
    for(i=0;i<((h*2)-1);i++){
      getline(cin,s);
      //cout<<i<<":"<<s<<endl;
      if(i%2==0){
        for(j=1;j<s.length();j+=2){
          if(s[j]=='1'){
            maze[i/2][j/2]+=8;
            maze[i/2][(j/2)+1]+=2;
          }
        }
      }
      else{
        for(j=0;j<s.length();j+=2){
          if(s[j]=='1'){
            maze[i/2][j/2]+=4;
            maze[(i/2)+1][j/2]+=1;
          }
        }
      }
    }
    solve(0,0,1);
    /*
    cout<<":"<<endl;
    for(i=0;i<h;i++){
      for(j=0;j<w;j++){
        //cout<<d[i][j]<<" ";
        printf("%3d ",d[i][j]);
      }
      cout<<endl;
    }
    cout<<":";
    */
    if(d[h-1][w-1]==INF) cout<<0<<endl;
    else cout<<d[h-1][w-1]<<endl;
  }
  return 0;
}