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)
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <utility>
using namespace std;

const int MAX_N = 30;
const int INF = (1 << 28);

typedef pair<int, int> P;

struct Masu {
    bool u, d, l, r;
};

// ?????????????????????
int dx[4] = {-1, 0, 0, 1};
int dy[4] = {0, -1, 1, 0};

int d[MAX_N][MAX_N];

int main(void) {
    int w, h;
    while (cin >> w >> h, w) {
        vector<vector<Masu>> maze(h, vector<Masu>(w));
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                maze[i][j].u = maze[i][j].d = maze[i][j].l = maze[i][j].r = false;
            }
        }
        for (int j = 1; j < w; j++) {
            maze[0][j].u = true;
        }
        for (int j = 0; j < w-1; j++) {
            maze[h-1][j].d = true;
        }
        for (int i = 0; i < h; i++) {
            maze[i][0].l = true;
            maze[i][w-1].r = true;
        }

        int tmp;
        for (int i = 1; i < 2*h; i++) {
            if (i%2) {
                for (int j = 1; j < w; j++) {
                    cin >> tmp;
                    if (tmp) {
                        maze[i/2][j-1].r = true;
                        maze[i/2][j].l = true;
                    }
                }
            } else {
                for (int j = 0; j < w; j++) {
                    cin >> tmp;
                    if (tmp) {
                        maze[i/2-1][j].d = true;
                        maze[i/2][j].u = true;
                    }
                }
            }
        }

        queue<P> que;
        for (int i = 0; i < MAX_N; i++) {
            for (int j = 0; j < MAX_N; j++) {
                d[i][j] = INF;
            }
        }

        que.push(P(0, 0));
        d[0][0] = 1;

        while (!que.empty()) {
            P p = que.front(); que.pop();
            if (p.first == w-1 && p.second == h-1) break;

            for (int i = 0; i < 4; i++) {
                bool flag = false;
                switch (i) {
                case 0:
                    if (maze[p.second][p.first].l) flag = true;
                    break;
                case 1:
                    if (maze[p.second][p.first].u) flag = true;
                    break;
                case 2:
                    if (maze[p.second][p.first].d) flag = true;
                    break;
                case 3:
                    if (maze[p.second][p.first].r) flag = true;
                    break;
                }
                if (flag) continue;

                int nx = p.first + dx[i];
                int ny = p.second + dy[i];

                if (0 <= nx && nx < w && 0 <= ny && ny < h) {
                    if (d[ny][nx] == INF) {
                        que.push(P(nx, ny));
                        d[ny][nx] = d[p.second][p.first] + 1;
                    }
                }
            }
        }

        if (d[h-1][w-1] != INF) {
            cout << d[h-1][w-1] << endl;
        } else {
            cout << 0 << endl;
        }
    }

    return 0;
}