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 long long L;
L w,h,grid[31][31][5],dist[31][31],flg=0;
L X[]={0,1,0,-1};
L Y[]={1,0,-1,0};
void reset(){
    memset(grid,0,sizeof(grid));
    memset(dist,0,sizeof(dist));
    flg=0;
}
void dfs(L x,L y){
    if(x==h&&y==w){
        flg=1;
        return ;
    }
    for(L i=0;i<4;i++){
        L xx=X[i]+x,yy=Y[i]+y;
        if(xx==1&&yy==1)continue;
        if(xx>0&&xx<=h && yy>0&&yy<=w){
            if(i==0){
                if(grid[x][y][0]){
                    if(dist[xx][yy]==0){
                        dist[xx][yy]=dist[x][y]+1;
                        //cout<<"in >> "<<xx<<" "<<yy<<endl;
                        dfs(xx,yy);
                        //cout<<"out >> "<<xx<<" "<<yy<<endl;
                    }
                    else{
                        if(dist[xx][yy]>dist[x][y]+1){
                            dist[xx][yy]=dist[x][y]+1;
                            //cout<<"in >> "<<xx<<" "<<yy<<endl;
                            dfs(xx,yy);
                            //cout<<"out >> "<<xx<<" "<<yy<<endl;
                        }
                    }
                }
            }
            else if(i==1){
                if(grid[x][y][1]){
                    if(dist[xx][yy]==0){
                        dist[xx][yy]=dist[x][y]+1;
                        //cout<<"in >> "<<xx<<" "<<yy<<endl;
                        dfs(xx,yy);
                        //cout<<"out >> "<<xx<<" "<<yy<<endl;
                    }
                    else{
                        if(dist[xx][yy]>dist[x][y]+1){
                            dist[xx][yy]=dist[x][y]+1;
                            //cout<<"in >> "<<xx<<" "<<yy<<endl;
                            dfs(xx,yy);
                            //cout<<"out >> "<<xx<<" "<<yy<<endl;
                        }
                    }
                }
            }
            else if(i==2){
                if(grid[x][y][2]){
                    if(dist[xx][yy]==0){
                        dist[xx][yy]=dist[x][y]+1;
                        //cout<<"in >> "<<xx<<" "<<yy<<endl;
                        dfs(xx,yy);
                        //cout<<"out >> "<<xx<<" "<<yy<<endl;
                    }
                    else{
                        if(dist[xx][yy]>dist[x][y]+1){
                            dist[xx][yy]=dist[x][y]+1;
                            //cout<<"in >> "<<xx<<" "<<yy<<endl;
                            dfs(xx,yy);
                            //cout<<"out >> "<<xx<<" "<<yy<<endl;
                        }
                    }
                }
            }
            else if(i==3){
                if(grid[x][y][3]){
                    if(dist[xx][yy]==0){
                        dist[xx][yy]=dist[x][y]+1;
                        //cout<<"in >> "<<xx<<" "<<yy<<endl;
                        dfs(xx,yy);
                        //cout<<"out >> "<<xx<<" "<<yy<<endl;
                    }
                    else{
                        if(dist[xx][yy]>dist[x][y]+1){
                            dist[xx][yy]=dist[x][y]+1;
                            //cout<<"in >> "<<xx<<" "<<yy<<endl;
                            dfs(xx,yy);
                            //cout<<"out >> "<<xx<<" "<<yy<<endl;
                        }
                    }
                }
            }
        }
    }
}
int main()
{
    while(scanf("%lld%lld",&w,&h)&& w||h ){
        L r=h,c=w,b;
        for(L i=1;i<=r;i++){
            if(i!=r){
                for(L j=1;j<c;j++){
                    scanf("%lld",&b);
                    if(!b){
                        grid[i][j][0]=1;grid[i][j+1][2]=1;
                    }
                }
                for(L j=1;j<=c;j++){
                    scanf("%lld",&b);
                    if(!b){
                        grid[i][j][1]=1;grid[i+1][j][3]=1;
                    }
                }
            }
            else{
                for(L j=1;j<c;j++){
                    scanf("%lld",&b);
                    if(!b){
                        grid[i][j][0]=1;grid[i][j+1][2]=1;
                    }
                }
            }
        }
        dfs(1,1);
        if(flg)printf("%lld\n",(dist[h][w])+1);
        else printf("0\n");
        reset();
    }
    return 0;
}
/*
6 5
0 1 0 0 1
0 0 1 0 1 1
0 1 1 0 0
0 1 0 0 1 0
1 1 0 1 0
0 1 1 0 0 1
0 1 1 1 0
0 1 1 0 0 1
0 0 0 1 0

*/