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: #!usr/bin/env python3
from collections import defaultdict,deque
from heapq import heappush, heappop
from itertools import permutations
import sys
import math
import bisect
def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS():return [list(x) for x in sys.stdin.readline().split()]
def S():
    res = list(sys.stdin.readline())
    if res[-1] == "\n":
        return res[:-1]
    return res
def IR(n):
    return [I() for i in range(n)]
def LIR(n):
    return [LI() for i in range(n)]
def SR(n):
    return [S() for i in range(n)]
def LSR(n):
    return [LS() for i in range(n)]

sys.setrecursionlimit(1000000)
mod = 1000000007

d = [(1,0),(-1,0),(0,1),(0,-1)]
def solve(h,w):
    s = LIR(2*h-1)
    bfs = [[0]*w for i in range(h)]
    bfs[0][0] = 1
    q = deque([(0,0)])
    g = (h-1,w-1)
    while q:
        y,x = q.popleft()
        if (y,x) == g:
            print(bfs[y][x])
            return
        nb = bfs[y][x]+1
        for dy,dx in d:
            ny,nx = y+dy,x+dx
            if 0 <= ny < h and 0 <= nx < w:
                if dy and not s[2*min(y,ny)+1][nx]:
                    if not bfs[ny][nx]:
                        bfs[ny][nx] = nb
                        q.append((ny,nx))
                elif dx and not s[2*ny][min(x,nx)]:
                    if not bfs[ny][nx]:
                        bfs[ny][nx] = nb
                        q.append((ny,nx))
    print(0)
    return

#Solve
if __name__ == "__main__":
    while 1:
        w,h = LI()
        if w == h == 0:
            break
        solve(h,w)

Python: # -*- coding:utf-8 -*-

def solve():
    import sys
    from collections import deque

    while True:
        W, H = map(int, sys.stdin.readline().split())
        if W==0 and H==0: break

        grid = []
        for i in range(H*2-1):
            _in = sys.stdin.readline().rstrip("\n")
            if i%2==0:
                _in += " "
            grid.append(list(_in))

        dist = [[0 for _ in range(W*2-1)] for __ in range(H*2-1)]
        dist[0][0] = 1
        que = deque([(0, 0)])

        while que:
            y, x = que.popleft()
            if grid[y][x] == "x": continue
            grid[y][x] = "x"

            if y==H*2-2 and x==W*2-2:
                # ゴールに到着できた
                break
            # for i in range(len(grid)):
            #     print(grid[i])
            # print()
            # input()

            for ny, nx, direct in ((y-1,x,"up"), (y+1,x,"down"), (y,x-1,"left"), (y,x+1,"right")):
                if ny==-1 or ny==(H*2-1) or nx==-1 or nx==(W*2-1): continue
                if grid[ny][nx] != "0": continue
                if direct=="up" and grid[ny-1][nx]!="x":
                    dist[ny-1][nx] = dist[y][x] + 1
                    que.append((ny-1, nx))
                elif direct=="down" and grid[ny+1][nx]!="x":
                    dist[ny+1][nx] = dist[y][x] + 1
                    que.append((ny+1, nx))
                elif direct=="left" and grid[ny][nx-1]!="x":
                    dist[ny][nx-1] = dist[y][x] + 1
                    que.append((ny, nx-1))
                elif direct=="right" and grid[ny][nx+1]!="x":
                    dist[ny][nx+1] = dist[y][x] + 1
                    que.append((ny, nx+1))

        print(dist[H*2-2][W*2-2])


if __name__ == "__main__":
    solve()

Python: from collections import deque

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

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

    if w == 0:
        exit()

    wall = [list(map(int, input().split())) for _ in range(2 * h - 1)]

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

    q = deque()
    q.append((0, 0))

    while q:
        sy, sx = q.popleft()
        for i in range(4):
            ty = sy + dy[i]
            tx = sx + dx[i]
            if 0<=tx<w and 0<=ty<h and d[ty][tx] == 0 and wall[sy + ty][(sx + tx) // 2] != 1:
                d[ty][tx] = d[sy][sx] + 1
                q.append((ty, tx))

    print(d[-1][-1])