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: # http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1166&lang=jp
from collections import deque
import sys
read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines

def main():
    ans = []

    while True:
        w, h = map(int, readline().split())
        if (w, h) == (0, 0):
            break
        
        c = [[0]*(2 * w + 1) for _ in range(2 * h + 1)]
        for j in range(2 * w + 1):
            c[0][j] = 1
            c[2*h][j] = 1
        for i in range(1,2*h):
            c[i][0] = 1
            c[i][2*w] = 1
        for i, _ in enumerate(range(2 * h - 1)):
            if i % 2 == 0:
                S = [int(x) for x in readline().split()]
                for j, s in zip(range(2,2*w+1,2), S):
                    c[i+1][j] = s
            else:
                S = [int(x) for x in readline().split()]
                for j, s in zip(range(1,2*w+1,2), S):
                    c[i+1][j] = s
        
        seen = [[-1]*w for _ in range(h)]
        
        # bfsによる最短経路探索
        queue = deque([(0, 0)])
        seen[0][0] = 1
        possible = False
        while queue:
            x, y = queue.popleft()
            cx, cy = 2*x + 1, 2*y + 1
            if (x, y) == (h-1, w-1):
                possible = True
                ans.append(seen[x][y])
                break

            dx = [1, 0, -1, 0]
            dy = [0, 1, 0, -1]
            for i in range(4):
                nx = x + dx[i]
                ny = y + dy[i]
                ncx = cx + dx[i]
                ncy = cy + dy[i]
                
                if c[ncx][ncy] == 0 and seen[nx][ny] == -1:
                    seen[nx][ny] = seen[x][y] + 1
                    queue.append((nx, ny))

        if not possible:
            ans.append(0)
    
    print("\n".join(map(str, ans)))


if __name__ == "__main__":
    main()

Python: import sys
from collections import deque

input = sys.stdin.readline
digtmp = [(0,1), (1,0), (0,-1), (-1,0)]

def solve():
    W, H = map(int, input().split())
    if W == 0 and H == 0:
        return -1
    h_cnt = 0
    wallset = set()
    for i in range(2*H-1):
        wallflag = list(map(int, input().split()))
        if i%2 == 0:
            for j, wf in enumerate(wallflag):
                if wf == 1:
                    wallset.add( frozenset( ((h_cnt, j), (h_cnt, j+1)) ) )
        else:
            for j, wf in enumerate(wallflag):
                if wf == 1:
                    wallset.add( frozenset( ((h_cnt, j), (h_cnt+1, j)) ) )
            h_cnt += 1

    #BFS
    field = [[0]*W for i in range(H)]
    field[0][0] = 1
    que = deque([(0,0)])
    while True:
        fr_x, fr_y = que.popleft()
        cnt = field[fr_x][fr_y]
        for d_x, d_y in digtmp:
            to_x = fr_x + d_x
            to_y = fr_y + d_y
            if 0 <= to_x < H and 0 <= to_y < W:
                wallcheck = set(((fr_x, fr_y), (to_x, to_y)))
                if wallcheck in wallset:
                    continue
                if field[to_x][to_y] == 0:
                    field[to_x][to_y] = cnt + 1
                    que.append((to_x, to_y))
        if len(que) == 0:
            break
    
    #ans
    ans = field[H-1][W-1]
    print(ans)
    return 0

def main():
    status = 0
    while status == 0:
        status = solve()
            
if __name__ == "__main__":
    main()