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 <bits/stdc++.h>

using namespace std;

//ABC007-Cの問題

struct mazepoint {
	int y;
	int x;
};

void mazedisp(vector<vector<int>> &maze, int h, int w) {
	for (int i = 0; i < h; i++) {
		for (int j = 0; j < w; j++) {
			cout << maze[i][j];
		}
		cout << endl;
	}
	cout << endl;
}

int main() {
	while (1) {
		int w, h;
		cin >> w >> h;

		if (w == 0 && h == 0) { return 0; }

		w = w * 2 + 3;
		h = h * 2 + 3;

		int sy, sx;
		int gy, gx;
		sy = 0; sx = 2;
		gy = h - 1; gx = w - 3;

		vector<int> mukix{ 1,0,-1,0 };
		vector<int> mukiy{ 0,1,0,-1 };

		//迷路読み込み
		vector<vector<int>> maze(h, vector<int>(w));
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				//			mazedisp(maze, h, w);
				if (i == 0 || i == h - 1 || j == 0 || j == w - 1
					|| i == 1 || i == h - 2 || j == 1 || j == w - 2) {
					maze[i][j] = 1;
					continue;
				}
				if (i % 2 == 0 && j % 2 == 0) {
					maze[i][j] = 0;
					continue;
				}
				if (i % 2 != 0 && j % 2 != 0) {
					maze[i][j] = 1;
					continue;
				}
				cin >> maze[i][j];
			}
		}
		maze[0][2] = 0;
		maze[1][2] = 0;
		maze[h - 1][w - 3] = 0;
		maze[h - 2][w - 3] = 0;

//		mazedisp(maze, h, w);

		//幅優先探索処理
		vector<vector<bool>> seen(h, vector<bool>(w));	//発見したらtrue
		deque<mazepoint> todo;					//行く所のスタック

		todo.push_back({ sy, sx });
		mazepoint s = todo.front();							//今いる場所

		seen[s.y][s.x] = true;
		vector<vector<int>> fukasa(h, vector<int>(w, 0));
		bool brkflg = false;
		while (todo.empty() != true) {				//スタックが空になるまで処理	
			s = todo.front();						//処理番号を指定
			int tugiflg = false;					//次があったらtrueにするフラグ
			for (int i = 0; i < 4; i++) {
				if (s.y + mukiy[i] < 0 || s.x + mukix[i] < 0
					|| s.y + mukiy[i] >h - 1 || s.x + mukix[i] > w - 1) {
					continue;
				}
				if (s.y + mukiy[i] == gy && s.x + mukix[i] == gx) {
					cout << (fukasa[s.y][s.x] - 1) / 2 << endl;
					brkflg = true;
					break;
				}

				if (maze[s.y + mukiy[i]][s.x + mukix[i]] == 1) { continue; }

				if (seen[s.y + mukiy[i]][s.x + mukix[i]] != true) {
					seen[s.y + mukiy[i]][s.x + mukix[i]] = true;
					todo.push_back({ s.y + mukiy[i],s.x + mukix[i] });
					fukasa[s.y + mukiy[i]][s.x + mukix[i]] = fukasa[s.y][s.x] + 1;
					tugiflg = true;
					//				cout << s.y + mukiy[i] << " " << s.x + mukix[i] << endl;
				}
			}
			if (brkflg) { break; }
			todo.pop_front(); //次を全部探したので削除する
	//		mazedisp(fukasa, h, w);
		}
		if (brkflg != true) {
			cout << 0 << endl;
		}
		//	mazedisp(fukasa, h, w);
	}
	return 0;

}