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)
}

Python: class Room:
    def __init__(self, row, col, ROWS, COLS):
        self.row = row
        self.col = col
        self.dist = None
        self.top = True if row > 0 else False
        self.left = True if col > 0 else False
        self.right = True if col < COLS - 1 else False
        self.bot = True if row < ROWS - 1 else False

if __name__ == '__main__':
    while True:
        COLS, ROWS = list(map(int, input().strip().split()))
        if ROWS == 0 and COLS == 0:
            break

        maze = [ [ Room(row, col, ROWS, COLS) for col in range(COLS) ] for row in range(ROWS) ]

        row = 0
        while True:
            walls = list(map(int, input().strip().split()))
            for col in range(COLS - 1):
                if walls[col] == 1:
                    maze[row][col].right = False
                    maze[row][col + 1].left = False
            
            if row == ROWS - 1:
                break
            
            walls = list(map(int, input().strip().split()))
            for col in range(COLS):
                if walls[col] == 1:
                    maze[row][col].bot = False
                    maze[row + 1][col].top = False

            row += 1

        maze[0][0].dist = 1
        processList = [ (0,0) ]
        while len(processList) > 0:
            row, col = processList.pop(0)
            room = maze[row][col]

            if room.top:
                rr = row - 1
                cc = col
                adjRoom = maze[rr][cc]
                if adjRoom.dist == None:
                    adjRoom.dist = room.dist + 1
                    processList.append((rr, cc))

            if room.bot:
                rr = row + 1
                cc = col
                adjRoom = maze[rr][cc]
                if adjRoom.dist == None:
                    adjRoom.dist = room.dist + 1
                    processList.append((rr, cc))

            if room.left:
                rr = row
                cc = col - 1
                adjRoom = maze[rr][cc]
                if adjRoom.dist == None:
                    adjRoom.dist = room.dist + 1
                    processList.append((rr, cc))

            if room.right:
                rr = row
                cc = col + 1
                adjRoom = maze[rr][cc]
                if adjRoom.dist == None:
                    adjRoom.dist = room.dist + 1
                    processList.append((rr, cc))

        dist = maze[ROWS - 1][COLS - 1].dist
        print(dist if dist != None else 0)