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 <queue>

using namespace std;

#define all(x) x.begin(), x.end()

const int dx[] = { 1, 0, -1, 0 };
const int dy[] = { 0, 1, 0, -1 };

struct state { int y, x, step; };

int main() {
        int w, h;
        while (cin >> w >> h && w) {
                int can[33][33][4];
                bool used[33][33];
                for (int i = 0; i < 33; i ++) {
                        for (int j = 0; j < 33; j ++) {
                                for (int d = 0; d < 4; d ++) {
                                        can[i][j][d] = true;
                                }
                        }
                }
                memset(used, 0, sizeof(used));
                for (int y = 0; y < 2 * h - 1; y ++) {
                        int ww = (y % 2 == 0 ? w - 1: w);
                        for (int x = 0; x < ww; x ++) {
                                int a;
                                cin >> a;
                                if (a == 1) { 
                                        if (y % 2 == 0) {
                                                can[y / 2][x][0] = false;
                                                can[y / 2][x + 1][2] = false;
                                        } else {
                                                can[y / 2][x][1] = false;
                                                can[y / 2 + 1][x][3] = false;
                                        }
                                }
                        }
                }
                queue<state> q;
                q.push((state) { 0, 0, 0 });
                used[0][0] = true;
                int ans = 0x3f3f3f3f;
                while (!q.empty()) {
                        state s = q.front(); q.pop();
                        if (s.y == h - 1 && s.x == w - 1) {
                                ans = s.step;
                                break;
                        }
                        for (int d = 0; d < 4; d ++) {
                                int yy = s.y + dy[d], xx = s.x + dx[d];
                                if (yy < 0 || yy > h - 1 || xx < 0 || xx > w - 1) continue;
                                if (!can[s.y][s.x][d]) continue;
                                if (used[yy][xx]) continue;
                                used[yy][xx] = true;
                                q.push((state) { yy, xx, s.step + 1 });
                        }
                }
                cout << (ans == 0x3f3f3f3f ? 0 : ans + 1) << endl;
        }
        return 0;
}

C++: #include <cstdio>
#include <queue>
#include <algorithm>

#define N 30

using namespace std;

struct P
{
  int c;
  int x;
  int y;

  P (
    const int c = 1,
    const int x = 0,
    const int y = 0
    )
  {
    this->c = c;
    this->x = x;
    this->y = y;
  }
};
typedef struct P P;

int
main (
  )
{
  int i, j;

  for ( ; ; )
  {
    queue<P> lis;
    int d[ N ][ N ] = { { 1 } };
    int v[ N ][ N ][ 4 ] = { };
    int w, h;

    scanf ( "%d%d", &w, &h );
    if ( !( w | h ) ) break ;

    for ( i = 0; i < h; ++i )
    {
      if ( i > 0 )
      for ( j = 0; j < w; ++j )
      {
        int G__21;

        scanf ( "%d", &G__21 );
        v[ i ][ j - 1 ][ 1 ] =
        v[ i ][ j ][ 3 ] = G__21;
      }

      for ( j = 0; j < w - 1; ++j )
      {
        int G__21;

        scanf ( "%d", &G__21 );
        v[ i ][ j ][ 0 ] =
        v[ i ][ j + 1 ][ 2 ] = G__21;
      }
    }

    lis.push ( P ( ) );
    for ( ; ; )
    {
      P p = lis.front ( );
      lis.pop ( );

      if ( p.x == w - 1 && p.y == h - 1 )
      {
        printf ( "%d\n", p.c );
        break ;
      }

      if ( p.x < w - 1
        && !d[ p.y ][ p.x + 1 ]
        && !v[ p.y ][ p.x ][ 0 ] )
      {
        d[ p.y ][ p.x + 1 ] = 1;
        lis.push ( P ( p.c + 1, p.x + 1, p.y ) );
      }
      if ( p.y < h - 1
        && !d[ p.y + 1 ][ p.x ]
        && !v[ p.y ][ p.x ][ 1 ] )
      {
        d[ p.y + 1 ][ p.x ] = 1;
        lis.push ( P ( p.c + 1, p.x, p.y + 1 ) );
      }
      if ( p.x > 0
        && !d[ p.y ][ p.x - 1 ]
        && !v[ p.y ][ p.x ][ 2 ] )
      {
        d[ p.y ][ p.x - 1 ] = 1;
        lis.push ( P ( p.c + 1, p.x - 1, p.y ) );
      }
      if ( p.y > 0
        && !d[ p.y - 1 ][ p.x ]
        && !v[ p.y ][ p.x ][ 3 ] )
      {
        d[ p.y - 1 ][ p.x ] = 1;
        lis.push ( P ( p.c + 1, p.x, p.y - 1 ) );
      }

      if ( lis.empty ( ) )
      {
        puts ( "0" );
        break ;
      }
    }
  }

  return ( 0 );
}