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 <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()
#define TOP 1
#define RIGHT 2
#define BOTTOM 4
#define LIFT 8
#define INF 1<<30

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef pair<int, P> iP;

const int dy[] = { -1, 0, 1, 0 };
const int dx[] = {  0, 1, 0,-1 };

short maze[35][35];
int visit[35][35];
int main()
{
//	cut here before submit 
//	freopen ("testcase.Amazing_Mazes", "r", stdin );
	int w, h;
//	while (cin >> w >> h, w, h ){
	while (1 ){
		cin >> w >> h;
		if (w == 0 && h == 0 ) break;
		memset (maze, 0, sizeof (maze ) );
		rep (i, h ) rep (j, w ) maze[i][j] = (TOP|RIGHT|BOTTOM|LIFT);
		rep (i, h ){
			maze[i][0] &= ~LIFT;
			maze[i][w-1] &= ~RIGHT;
		} // end rep
		rep (j, w ){
			if (j != 0 ) maze[0][j] &= ~TOP;
			if (j != w - 1 ) maze[h-1][j] &= ~BOTTOM;
		} // end rep
		rep (i, 2*h-1 ){
			if (i % 2 == 0 ){
				rep (j, w-1 ){
					int in;
					cin >> in;
					if (in == 1 ){
						maze[i/2][j] &= ~RIGHT;
						maze[i/2][j+1] &= ~LIFT;
					} // end if
				} // end rep
			}else{
				rep (j, w ){
					int in;
					cin >> in;
					if (in == 1 ){
						maze[i/2][j] &= ~BOTTOM;
						maze[i/2+1][j] &= ~TOP;
					} // end if
				} // end rep
			} // end if
		} // end rep
//		memset (visit, -1, sizeof (visit ) );
		rep (i, h ) rep (j, w ) visit[i][j] = INF;

		priority_queue<iP, vector<iP>, greater<iP> > que;
		que.push (iP (1, P(0, 0 ) ) );
		visit[0][0] = 1;
		while (!que.empty() ){
			iP curr = que.top(); que.pop();
			int cc = curr.first;
			int cy = curr.second.first;
			int cx = curr.second.second;
			if (cy == h - 1 && cx == w - 1 ) break;
//			visit[cy][cx] = cc;
			rep (k, 4 ){
				int ny = cy + dy[k];
				int nx = cx + dx[k];
				if ((maze[cy][cx] & (1<<k ) ) == 0 ) continue;
				if (nx < 0 || nx >= w || ny < 0 || ny >= h ) continue;
//				if (visit[ny][nx] != -1 && visit[ny][nx] < cc ) continue;
//				visit[ny][nx] = cc + 1;
//				if (visit[ny][nx] == -1 || visit[ny][nx] > cc + 1 )
				if (cc+1 >= visit[ny][nx] ) continue;
				visit[ny][nx] = cc + 1;
				que.push (iP(cc + 1,  P (ny, nx ) ) );
			} // end rep
		} // end while
		
		if (visit[h-1][w-1] == INF ){
			cout << 0 << endl;
		}else{
			cout << visit[h-1][w-1] << endl;
		} // end if
/*
		rep (i, h ){
			rep (j, w ){
				cout << setw(2) << maze[i][j];
			} // end rep
			cout << endl;
		} // end rep
*/
	} // end loop

//	printf ("%d\n", res );
		
	return 0;
}