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: # coding: utf-8

import sys
from collections import deque

if __name__ == '__main__':
    while True:
        m,n = map(int,input().split())
        sw = []
        bw = []
        if m == 0 and n == 0:
            break
        for i in range(2*n-1):
            if i % 2 == 0:
                sw.append(list(map(int,input().split())))
            else:
                bw.append(list(map(int,input().split())))
        flag = [[0 for i in range(m)] for j in range(n)]
        deq = deque()
        deq.append([0,0,1])
        res = 0
        while len(deq) != 0:
            bf = deq[0]
            deq.popleft()
            if bf[0] == n-1 and bf[1] == m-1:
                res = bf[2]
                break
            flag[bf[0]][bf[1]] = 1
            if 1 <= bf[0] and bw[bf[0]-1][bf[1]] == 0 and flag[bf[0]-1][bf[1]] == 0:
                deq.append([bf[0]-1,bf[1],bf[2]+1])
            if bf[1] < m-1 and sw[bf[0]][bf[1]] == 0 and flag[bf[0]][bf[1]+1] == 0:
                deq.append([bf[0],bf[1]+1,bf[2]+1])
            if 1 <= bf[1] and sw[bf[0]][bf[1]-1] == 0 and flag[bf[0]][bf[1]-1] == 0:
                deq.append([bf[0],bf[1]-1,bf[2]+1])
            if bf[0] < n-1 and bw[bf[0]][bf[1]] == 0 and flag[bf[0]+1][bf[1]] == 0:
                deq.append([bf[0]+1,bf[1],bf[2]+1])
        print(res)

Python: from collections import deque

def cat_go(x,y,nx,ny):
    if x == nx:
        return 1-wall[2*x][min(ny,y)]
    else:
        return 1-wall[2*min(x,nx)+1][y]

def bfs():
    global mapp
    mapp[0][0] = 1
    que = deque()
    que.append([0,0])
    while que:
        place = que.popleft()
        x = place[0];y = place[1]
        #end
        if x == h-1 and y == w-1:
            return mapp[x][y]
        for d in [[1,0],[0,1],[-1,0],[0,-1]]:
            nx = x + d[0];ny = y + d[1]
            #forbidden
            if not (0<=nx and nx<h and 0<=ny and ny<w):continue
            if not cat_go(x,y,nx,ny):continue
            #wont go
            if mapp[nx][ny] != 0:continue
            #go
            mapp[nx][ny] = mapp[x][y]+1
            que.append([nx,ny])
    return 0

while True:
    w,h = map(int,input().split())
    if w==0 and h==0:exit()
    mapp = [[0] * w for _ in range(h)]
    wall = []
    for i in range(2*h-1):
        wall.append(list(map(int,input().split())))
    print(bfs())

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

from heapq import heappop,heappush

def bfs(sx,sy,W,H):
    queue = []
    heappush(queue,(0,sx,sy))
    dxdy = [(0,1),(0,-1),(1,0),(-1,0)]
    visited = [[ 10**8 for i in range(W)] for j in range(H)]

    while queue != []:
        count,x,y = heappop(queue)
        if visited[y][x] != 10**8:
            continue
        visited[y][x] = count
        for nx,ny in dxdy:
            if 0 <= x + nx < W and 0 <= y + ny < H:
                if visited[y + ny][x + nx] == 10**8:
                    nextValue = Maze[y + ny][x + nx]
                    if ((nx,ny) == (1,0) and nextValue & 1 > 0) or ((nx,ny) == (0,1) and nextValue & 2 > 0) or ((nx,ny) == (-1,0) and Maze[y][x] & 1 > 0) or ((nx,ny) == (0,-1) and Maze[y][x] & 2 > 0 ):
                        continue
                    else:
                        heappush(queue,(count + 1,x+nx,y+ny))
    return visited

while True:
    w,h = map(int,input().split(" "))
    if h == 0 and w == 0:
        break
    Maze = [[0 for j in range(w)] for i in range(h)]
    for i in range(h-1):
        row = list(map(int,input().split()))
        for j in range(len(row)):
            if row[j] == 1:
                Maze[i][j+1] += 1
        col = list(map(int,input().split()))
        for j in range(len(col)):
            if col[j] == 1:
                Maze[i+1][j] += 2
    else:
        i += 1
        row = list(map(int,input().split()))
        for j in range(len(row)):
            if row[j] == 1:
                Maze[i][j+1] += 1

    ret = bfs(0,0,w,h)[h-1][w-1]
    print(ret + 1 if ret != 10**8 else 0)