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 <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
using namespace std;
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str();}
typedef vector<int> vi;
typedef vector<vi>  vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EACH(t,i,c) for(t::iretator i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n) FOR(i,0,n-1)
const double EPS = 1e-10;
const double PI = acos(-1.0);

#include <complex>
typedef complex<double> P;

struct L {
	P a, b;
	L(const P &a, const P &b) : a(a), b(b) { }
};

struct C {
	P p; double r;
	C(const P p, double r) : p(p), r(r) { }
};

double dot(P a, P b) {
	return real(conj(a)*b);
}

double cross(P a, P b) {
	return imag(conj(a)*b);
}

bool LLcross(L l1, L l2) {
	return abs(cross(l1.b-l1.a, l2.b-l2.a)) > EPS || abs(cross(l1.b-l1.a, l2.b-l1.a)) < EPS;
}

double dist(P p1, P p2) {
	return sqrt((p2.real()-p1.real())*(p2.real()-p1.real()) + (p2.imag()-p1.imag())*(p2.imag()-p1.imag()));
}

const int UE	 = 1;
const int MIGI	 = 2;
const int SHITA  = 4;
const int HIDARI = 8;
const int CHECK  = 16;

int dx[] = {-1, 0, 1, 0};
int dy[] = {0, 1, 0, -1};
int dk[] = {UE, MIGI, SHITA, HIDARI};

struct state {
	int x, y, t;
	state(int x, int y, int t) : x(x), y(y), t(t) {};
};

int main() {
	int w, h;

	while(cin >> w >> h, w) {
		vvi field(h, vi(w));
		
		REP(i, w) {
			field[0][i] += UE;
			field[h-1][i] += SHITA;
		}
		
		REP(i, h) {
			field[i][0] += HIDARI;
			field[i][w-1] += MIGI;
		}

		int tmp;
		REP(i, 2*h-1) {
			if(i%2 == 0) {
				REP(j, w-1) {
					cin >> tmp;
					if(tmp) {
						field[i/2][j] += MIGI;
						field[i/2][j+1] += HIDARI;
					}
				}
			} else {
				REP(j, w) {
					cin >> tmp;
					if(tmp) {
						field[i/2][j] += SHITA;
						field[i/2+1][j] += UE;
					}
				}
			}
		}

		queue<state> Q;
		Q.push(state(0, 0, 1));
		field[0][0] += CHECK;

		int ans = 0;
		while(!Q.empty()) {
			state s = Q.front();
			Q.pop();
			if(s.x == h-1 && s.y == w-1) {
				ans = s.t;
				goto out;
			}

			REP(d, 4) {
				if(field[s.x][s.y] & dk[d]) {

				} else {
					if(!(field[s.x+dx[d]][s.y+dy[d]] & CHECK)) {
						Q.push(state(s.x+dx[d], s.y+dy[d], s.t+1));
						field[s.x+dx[d]][s.y+dy[d]] += CHECK;
					}
				}
			}
		}

out:
		cout << ans << endl;
	}

	return 0;
}