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;
typedef tuple<int,int,int> T;
int dx[4]={1,0,-1,0};
int dy[4]={0,-1,0,1}; //????????????
bool wall[30][30][4];
bool vis[30][30];
int main() {
	int w,h;
	while(scanf("%d %d",&w,&h),w) {
		memset(wall,0,sizeof(wall));
		memset(vis,0,sizeof(vis));
		for(int i=0;i<h-1;i++) {
			for(int j=0;j<w-1;j++) {
				int a;
				scanf("%d",&a);
				if(a) wall[i][j][0]=wall[i][j+1][2]=1;
			}
			for(int j=0;j<w;j++) {
				int a;
				scanf("%d",&a);
				if(a) wall[i][j][3]=wall[i+1][j][1]=1;
			}
		}
		for(int i=0;i<w-1;i++) {
			int a;
			scanf("%d",&a);
			if(a) wall[h-1][i][0]=wall[h-1][i+1][2]=1;
		}
		queue<T> Q;
		Q.push(make_tuple(0,0,1));
		vis[0][0]=1;
		int ans=0;
		while(!Q.empty()) {
			T t=Q.front();Q.pop();
			int x=get<0>(t);
			int y=get<1>(t);
			int d=get<2>(t);
			if(x==w-1&&y==h-1) {ans=d;break;}
			for(int i=0;i<4;i++) {
				int nx=x+dx[i],ny=y+dy[i];
				if(wall[y][x][i]||0>nx||nx>=w||0>ny||ny>=h||vis[ny][nx]) continue;
				Q.push(make_tuple(nx,ny,d+1));
				vis[ny][nx]=1;
			}
		}
		printf("%d\n",ans);
	}
}

C++: #include "bits/stdc++.h"

using namespace std;

using ll = long long;

template<typename T> using V = std::vector<T>;
using Vi = V<int>;
using VVi = V<V<int>>;
using Vl = V<ll>;
using VVl = V<V<ll>>;
using Vs = V<string>;

template<typename T1, typename T2> using P = std::pair<T1, T2>;
using Pii = P<int, int>;
using Pll = P<ll, ll>;
using Pdd = P<double, double>;

template<typename T1, typename T2> using M = std::map<T1, T2>;
using Mii = M<int, int>;
using Msi = M<string, int>;

#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define REP2(i,s,e) for(int i=(int)(s);i<(int)(e);++i)
#define RREP(i,s,e) for(int i=(int)(s);i>=(int)(e);--i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin(),ie=(c).end();i!=ie;++i)
#define ALL(c) (c).begin(), (c).end()

const double PI = acos(-1);
const ll MOD = 1e9+7;

int n, h, w;
string s;
Vi dir = {1, 0, -1, 0, 1};

int main() {
    while (true) {
        cin >> w >> h;
        if (w == 0 && h == 0) {
            break;
        }

        V<VVi> wall(h, VVi(w, Vi(4, 0)));
        REP(i, 2*h-1) {
            int H = i/2;
            if (i%2 == 0) {
                REP(j, w-1) {
                    int x; cin >> x;
                    if (x == 1) {
                        wall[H][j][0] = 1;
                        wall[H][j+1][2] = 1;
                    }
                }
            } else {
                REP(j, w) {
                    int x; cin >> x;
                    if (x == 1) {
                        wall[H][j][3] = 1;
                        wall[H+1][j][1] = 1;
                    }
                }
            }
        }

        VVi dis(h, Vi(w, -1));
        queue<Pii> q;
        q.push({0, 0});
        dis[0][0] = 1;
        while (!q.empty()) {
            int y = q.front().first, x = q.front().second;
            q.pop();
            REP(i, 4) {
                int Y = y + dir[i+1], X = x + dir[i];
                if (Y < 0 || X < 0 || Y >= h || X >= w) continue;
                if (wall[y][x][i] == 1) continue;
                if (dis[Y][X] != -1) continue;
                dis[Y][X] = dis[y][x] + 1;
                q.push({Y, X});
            }
            if (dis[h-1][w-1] != -1) {
                std::cout << dis[h-1][w-1] << '\n';
                break;
            }
        }
        if (q.empty()) {
            std::cout << 0 << '\n';
        }
    }

    return 0;
}