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: while(1):
    w, h = map(int, input().split())
    if not h+w:
        break
    h = 2*h-1
    w = 2*w-1
    m = [[1] * (w+2) for i in range(h+2)]
    for j in range(1, h+1):
        a = [int(i) for i in input().split()] #適宜変える
        if j%2:
            m[j][1:w+1] = [0] * w
            for k in range(w//2):
                m[j][2*k+2] = a[k]
        else:
            for k in range(w-w//2):
                m[j][2*k+1] = a[k]

    dx = [0, 0, -1, 1]
    dy = [-1, 1, 0, 0]

    s = [1, 1]
    d = [[-1 for k in range(w+2)] for j in range(h+2)]
    todo = [s]
    d[s[0]][s[1]] = 0
    while(todo != []):
        v = todo.pop(0)
        for k in range(4):
            if m[v[0]+dx[k]][v[1]+dy[k]] != 1 and d[v[0]+dx[k]][v[1]+dy[k]] == -1:
                d[v[0]+dx[k]][v[1]+dy[k]] = d[v[0]][v[1]]+1
                todo.append([v[0]+dx[k], v[1]+dy[k]])
    print(d[-2][-2]//2+1 if d[-2][-2] != -1 else 0)

Python: def solve(w,h,row,col):
    check_map = [[False for i in range(w)] for j in range(h)]
    search_list = [[0, 0, 1]]
    check_map[0][0] = True
    ok = False
    while len(search_list) > 0:
        x, y, step = search_list.pop(0)
        if x == w-1 and y == h-1:
            return step
            ok = True
            break
        # 左
        if x > 0:
            if row[y][x-1] == "0" and not check_map[y][x-1]:
                search_list.append([x-1, y, step+1])
                check_map[y][x-1] = True
        # 右
        if x < w-1:
            if row[y][x] == "0" and not check_map[y][x+1]:
                search_list.append([x+1, y, step+1])
                check_map[y][x+1] = True
        # 上
        if y > 0:
            if col[y-1][x] == "0" and not check_map[y-1][x]:
                search_list.append([x, y-1, step+1])
                check_map[y-1][x] = True
        # 下
        if y < h-1:
            if col[y][x] == "0" and not check_map[y+1][x]:
                search_list.append([x, y+1, step+1])
                check_map[y+1][x] = True
    if not ok:
        return 0

while True:
    w, h = map(int, input().split())
    if w == 0:
        break
    row = []
    col = []
    for i in range(h-1):
        row.append(input().split())
        col.append(input().split())
    row.append(input().split())
    print(solve(w,h,row,col))

Python: # -*- coding: utf-8 -*-
from collections import defaultdict, deque
W, H = map(int, input().split())

while W:
    G = defaultdict(list)
    for h in range(H):
        for w, b in enumerate(map(int, input().split())):
            if b == 0:
                G[(w, h)].append((w+1, h))
                G[(w+1, h)].append((w, h))
        if h == H-1:
            break
        for w, b in enumerate(map(int, input().split())):
            if b == 0:
                G[(w, h)].append((w, h+1))
                G[(w, h+1)].append((w, h))

    dist = defaultdict(lambda: 1000)
    Q = deque([(0, 0)])
    dist[(0, 0)] = 1
    found = False
    while Q:
        x, y = Q.pop()
        c = dist[(x, y)]
        for px, py in G[(x, y)]:
            if (px, py) == (W-1, H-1):
                print(c+1)
                Q = []
                found = True
                break
            elif dist[(px, py)] > c+1:
                dist[(px, py)] = c+1
                Q.append((px, py))
    if not found:
        print(0)
    W, H = map(int, input().split())

Python: from collections import deque

ans = []
while True:
    w, h = map(int, input().split())

    if w == 0 and h == 0:
        break
    
    col = []
    row = []
    for i in range(2*h-1):
        if i % 2 == 0:
            col.append(list(map(int, input().split())))
        else:
            row.append(list(map(int, input().split())))
    
    dwdh = [(1, 0), (-1, 0), (0, 1), (0, -1)]

    d = [[0] * w for _ in range(h)]

    que = deque([(0, 0)])
    d[0][0] = 1
    while que:
        qw, qh = que.popleft()

        for dw, dh in dwdh:
            nw = qw + dw
            nh = qh + dh
            if not(0 <= nh < h) or not(0 <= nw < w) or d[nh][nw]:
                continue
            if (dh == -1 and row[nh][nw] == 1) or (dh == 1 and row[nh-1][nw]==1):
                continue
            if (dw == -1 and col[nh][nw] == 1) or (dw == 1 and col[nh][nw-1] == 1):
                continue

            que.append((nw, nh))
            d[nh][nw] = d[qh][qw] + 1

    ans.append(d[h-1][w-1])

for a in ans:
    print(a)