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: from collections import defaultdict,deque
import sys,heapq,bisect,math,itertools,string,queue,copy,time
sys.setrecursionlimit(10**8)
INF = float('inf')
mod = 10**9+7
eps = 10**-7
def inp(): return int(input())
def inpl(): return list(map(int, input().split()))
def inpl_str(): return list(input().split())

def calc(y,x):
    return y*W+x


def dijkstra(lines,N,s):
    weight = [INF]*N
    weight[s] = 0

    def search(s,w_0,q,weight):
        for t,w in lines[s]:
            w += w_0
            if weight[t] > w:
                heapq.heappush(q,[w,t])
                weight[t] = w

    q = [[0,s]]
    heapq.heapify(q)
    while q:
        w,n = heapq.heappop(q)
        search(n,w,q,weight)

    return weight



while True:
    W,H = inpl()
    if W==0 and H == 0:
        break
    else:
        lines = defaultdict(set)
        for i in range(2*H-1):
            if i%2 == 0:
                h = i//2
                ww = inpl()
                for i,w in enumerate(ww):
                    if w == 0:
                        lines[calc(h,i)].add((calc(h,i+1),1))
                        lines[calc(h,i+1)].add((calc(h,i),1))
            else:
                h = i//2
                ww = inpl()
                for i,w in enumerate(ww):
                    if w == 0:
                        lines[calc(h,i)].add((calc(h+1,i),1))
                        lines[calc(h+1,i)].add((calc(h,i),1))

        weight = dijkstra(lines,H*W,0)
        if weight[-1] == INF:
            print(0)
        else:
            print(weight[-1]+1)

Python: import sys
from collections import deque

while True:
    w, h = map(int, input().split())
    if w == 0 and h == 0:
        sys.exit()

    grid = [[0] * w for _ in range(h)]
    grid[0][0] = 1

    wall_tate = []
    wall_yoko = []

    for i in range(h * 2 - 1):
        if i % 2 == 0:
            wall_yoko.append(list(map(int, input().split())))
        else:
            wall_tate.append(list(map(int, input().split())))

    moves = [1, -1]

    q = deque([[0, 0]])

    while q:
        curr = q.popleft()

        # 縦移動
        for m in moves:
            nx, ny = curr[0] + m, curr[1]
            if 0 <= nx < h and 0 <= ny < w and grid[nx][ny] == 0:
                if wall_tate[min(curr[0], nx)][ny] == 0:
                    grid[nx][ny] = grid[curr[0]][curr[1]] + 1
                    q.append([nx, ny])

        # 横移動
        for m in moves:
            nx, ny = curr[0], curr[1] + m
            if 0 <= nx < h and 0 <= ny < w and grid[nx][ny] == 0:
                if wall_yoko[nx][min(curr[1], ny)] == 0:
                    grid[nx][ny] = grid[curr[0]][curr[1]] + 1
                    q.append([nx, ny])

    print(grid[-1][-1])

Python: import queue

def bfs(w, h, maze):
    dx = [-1, 0, 0, 1]
    dy = [0, 1, -1, 0]
    dist = [ [-1] * (w+1) for _ in range(h+1) ]
    q = queue.Queue()
    q.put([0, 0, 0])
    dist[0][0] = 0

    while not q.empty():
        x, y, d = q.get()
        for i in range(4):
            nx = x+dx[i]
            ny = y+dy[i]

            if maze[y][x][i] == 0: continue
            if dist[ny][nx] != -1: continue
            
            q.put( [nx, ny, d+1] )
            dist[ny][nx] = d+1

    return dist[h-1][w-1] + 1

while True:
    w, h = map(int, input().split())
    if w == 0 and h == 0: break
    maze = [ [[0] * 4 for x in range(w+1)] for _ in range(h+1) ]

    for i in range(h*2-1):
        if i & 1:
            t = [ int(x) for x in input().split() ]
            for j, tt in enumerate(t):
                if tt == 0:
                    maze[i//2][j][1] = 1
                    maze[i//2+1][j][2] = 1
        else:
            t = [ int(x) for x in input().split() ]
            for j, tt in enumerate(t):
                if tt == 0:
                    maze[i//2][j][3] = 1
                    maze[i//2][j+1][0] = 1
    print(bfs(w, h, maze))