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 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)]
    l = [(0,0,1)]
    res = 0
    while l:
        bf = l.pop(0)
        x,y,z = bf[0],bf[1],bf[2]
        if x == n-1 and y == m-1:
            res = z
            break
        flag[x][y] = 1
        if 1 <= x and bw[x-1][y] == 0 and flag[x-1][y] == 0:
            l.append((x-1,y,z+1))
        if y < m-1 and sw[x][y] == 0 and flag[x][y+1] == 0:
            l.append((x,y+1,z+1))
        if 1 <= y and sw[x][y-1] == 0 and flag[x][y-1] == 0:
            l.append((x,y-1,z+1))
        if x < n-1 and bw[x][y] == 0 and flag[x+1][y] == 0:
            l.append((x+1,y,z+1))
    print(res)

Python: from collections import deque


def main():
    ans = []
    while True:
        W, H = map(int, input().split())
        if W == 0 == H:
            break
        ipts = [input() if i % 2 == 1 else input()+" " for i in range(2*H-1)]
        v_wall = [[[False, False, False, False] for _ in range(W)] for _ in range(H)]
        for y in range(0, 2*H-1, 2):
            for x in range(0, 2*W-1, 2):
                for k in range(4):
                    dy, dx = moves[k]
                    ny, nx = y+dy, x+dx
                    if 0 <= ny < 2*H-1 and 0 <= nx < 2*W-1 and ipts[ny][nx] == "1":
                        v_wall[y//2][x//2][k] = True
        gd = 0
        que = deque([(0, 0, 1)])
        visited = set()
        visited.add((0, 0))
        while que:
            y, x, d = que.popleft()
            if y == H-1 and x == W-1:
                gd = d
                break
            for i in range(4):
                dy, dx = moves[i]
                ny, nx = y+dy, x+dx
                if 0 <= ny < H and 0 <= nx < W and not v_wall[y][x][i] and (ny, nx) not in visited:
                    que.append((ny, nx, d+1))
                    visited.add((ny, nx))
        ans.append(gd)
    for a in ans:
        print(a)


if __name__ == "__main__":
    moves = [(1, 0), (-1, 0), (0, 1), (0, -1)]
    main()

Python: # coding: utf-8

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)]
        l = [[0,0,1]]
        res = 0
        while l:
            bf = l[0]
            l.pop(0)
            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:
                l.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:
                l.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:
                l.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:
                l.append([bf[0]+1,bf[1],bf[2]+1])
        print(res)

Python: 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)]
    l = [(0,0,1)]
    res = 0
    while l:
        bf = l.pop(0)
        x,y,z = bf[0],bf[1],bf[2]
        if x == n-1 and y == m-1:
            res = z
            break
        if 1 <= x and bw[x-1][y] == 0 and flag[x-1][y] == 0:
            flag[x-1][y] = 1
            l.append((x-1,y,z+1))
        if y < m-1 and sw[x][y] == 0 and flag[x][y+1] == 0:
            flag[x][y+1] = 1
            l.append((x,y+1,z+1))
        if 1 <= y and sw[x][y-1] == 0 and flag[x][y-1] == 0:
            flag[x][y-1] = 1
            l.append((x,y-1,z+1))
        if x < n-1 and bw[x][y] == 0 and flag[x+1][y] == 0:
            flag[x+1][y] = 1
            l.append((x+1,y,z+1))
    print(res)