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 main(void){
    int w,h;
    while (cin>>w>>h) {
        if (w==0&&h==0) {
            break;
        }
        std::vector<vector<int>> vec(h*2+1,vector<int>(w*2+1));
        for (int i=0;i<h*2+1;i++) {
            for (int j=0;j<w*2+1;j++) {
                vec[i][j]=0;
            }
        }
        for (int i=0;i<h*2+1;i++) {
            vec[i][0]=-1;
            vec[i][w*2]=-1;
        }
        for (int i=0;i<w*2+1;i++) {
            vec[0][i]=-1;
            vec[h*2][i]=-1;
        }
        int a;
        for (int i=0;i<2*h-1;i++) {
            if (i%2==0) {
                for (int j=0;j<w-1;j++) {
                    cin>>a;
                    if (a==1) {
                        vec[i+1][(j+1)*2]=-1;
                    }
                }
            } else {
                for (int j=0;j<w;j++) {
                    cin>>a;
                    if (a==1) {
                        vec[i+1][j*2+1]=-1;
                    }
                }
            }
        }
        /*
        for (int i=0;i<h*2+1;i++) {
            for (int j=0;j<w*2+1;j++) {
                cout<<vec[i][j]<<" ";
            }cout<<endl;
        }*/
        std::deque<pair<int,int>> deq;
        deq.emplace_back(make_pair(1,1));
        vec[1][1]=1;
        int flag=0;
        while (deq.size()!=0) {
            int x=deq.front().first;
            int y=deq.front().second;
            if (x==h*2-1&&y==w*2-1) {
                cout<<vec[x][y]<<endl;
                flag=1;
                break;
            } else if (x+2<h*2+1&&vec[x+1][y]==0&&vec[x+2][y]==0) {
                deq.emplace_back(make_pair(x+2,y));
                vec[x+2][y]=vec[x][y]+1;
            } else if (y+2<w*2+1&&vec[x][y+1]==0&&vec[x][y+2]==0) {
                deq.emplace_back(make_pair(x,y+2));
                vec[x][y+2]=vec[x][y]+1;
            } else if (x-2>0&&vec[x-1][y]==0&&vec[x-2][y]==0) {
                deq.emplace_back(make_pair(x-2,y));
                vec[x-2][y]=vec[x][y]+1;
            } else if (y-2>0&&vec[x][y-1]==0&&vec[x][y-2]==0) {
                deq.emplace_back(make_pair(x,y-2));
                vec[x][y-2]=vec[x][y]+1;
            } else {
                deq.pop_front();
            }
        }
        /*
        for (int i=0;i<h*2+1;i++) {
            for (int j=0;j<w*2+1;j++) {
                if (vec[i][j]!=0) {
                    cout<<vec[i][j]<<" ";
                } else {
                    cout<<" "<<vec[i][j]<<" ";
                }
            }cout<<endl;
        }*/
        if (flag==0) {
            cout<<0<<endl;
        }
    }
}

C++: #include <cstdio>
#include <cstdlib>
#include <queue>
using namespace std;

#define N 30

static struct D
{
  int lf;
  int rt;
  int up;
  int dn;
  int mk;
  D ( ) { this->lf = this->rt = this->up = this->dn = 1; this->mk = 0; }
} d[ N ][ N ];
static int w;
static int h;

struct S
{
  int x;
  int y;
  int s;
  S ( int x, int y, int s ) { this->x = x; this->y = y; this->s = s; }
};

int
main (
  int   argc,
  char *argv[ ]
  )
{
  int i, j;

  for ( ; ; )
  {
    queue<S> lis;
    int res = 0;

    scanf ( "%d%d", &w, &h );
    if ( w == 0 && h == 0 )
      break ;

    for ( i = 0; i < h; ++i )
    for ( j = 0; j < w; ++j )
      d[ j ][ i ] = D ( );

    for ( i = 0; i < h; ++i )
    {
      for ( j = 0; j < w - 1; ++j )
      {
        scanf ( "%d", &d[ j ][ i ].rt );
        d[ j + 1 ][ i ].lf = d[ j ][ i ].rt;
      }

      if ( i < h - 1 )
      for ( j = 0; j < w; ++j )
      {
        scanf ( "%d", &d[ j ][ i ].dn );
        d[ j ][ i + 1 ].up = d[ j ][ i ].dn;
      }
    }

    lis.push ( S ( 0, 0, 1 ) );
    while ( !lis.empty ( ) )
    {
      const S s = lis.front ( );
      lis.pop ( );

      if ( s.x == w - 1 && s.y == h - 1 )
      {
        res = s.s;
        break ;
      }
      if ( d[ s.x ][ s.y ].mk )
        continue ;
      d[ s.x ][ s.y ].mk = 1;

      if ( d[ s.x ][ s.y ].lf == 0 ) lis.push ( S ( s.x - 1, s.y, s.s + 1 ) );
      if ( d[ s.x ][ s.y ].rt == 0 ) lis.push ( S ( s.x + 1, s.y, s.s + 1 ) );
      if ( d[ s.x ][ s.y ].up == 0 ) lis.push ( S ( s.x, s.y - 1, s.s + 1 ) );
      if ( d[ s.x ][ s.y ].dn == 0 ) lis.push ( S ( s.x, s.y + 1, s.s + 1 ) );
    }
    printf ( "%d\n", res );
  }

}