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 <set>
#ifndef LIB_REPEAT_HPP
#define LIB_REPEAT_HPP
#define repeat(i,n) for (int i = 0; i < (n); ++i)
#define repeat_from(i,m,n) for (int i = (m); i < (n); ++i)
#define repeat_one(i,n) for (int i = 1; i <= (n); ++i)
#define repeat_rev(i,n) for (int i = (n)-1; 0 <= i; --i)
#define foreach(it, cont) for (decltype(cont.begin()) it = cont.begin(); it != cont.end(); ++it)
#endif
using namespace std;
struct point { int x, y; };
bool operator < (const point & a, const point & b) { return a.x != b.x ? a.x < b.x : a.y < b.y; }
const point directions[] = { { 0, 1 }, { 0, -1 }, { -1, 0 }, { 1, 0 } };
point operator + (const point & a, const point & b) { return (point) { a.x + b.x, a.y + b.y }; }
struct cell { int x, y, cost; };
bool operator < (const cell & a, const cell & b) { return not (a.cost < b.cost); } // reversed
int main() {
    ios_base::sync_with_stdio(false);
    while (true) {
        int W, H; cin >> W >> H; cin.ignore();
        if (W == 0 and H == 0) break;
        vector<string> m(2*H-1);
        repeat (h,2*H-1) {
            getline(cin, m[h]);
            if (m[h].length() < 2*W-1) m[h] += ' ';
        }
        priority_queue<cell> que; que.push((cell) { 0, 0, 1 });
        set<point> used;
        int result = 0;
        while (not que.empty()) {
            const cell c = que.top(); que.pop();
            if (c.x == W-1 and c.y == H-1) {
                result = c.cost;
                break;
            }
            if (used.count((point) { c.x, c.y })) continue;
            used.insert((point) { c.x, c.y });
            repeat (d,4) {
                const point e = (point) { c.x, c.y } + directions[d];
                if (0 <= e.x and e.x < W and 0 <= e.y and e.y < H) {
                    if (m[c.y+e.y][c.x+e.x] == '0' and not used.count(e)) {
                        que.push((cell) { e.x, e.y, c.cost+1 });
                    }
                }
            }
        }
        cout << result << endl;
    }
    return 0;
}