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++: #pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define EPS (1e-7)
#define INF (1e9)
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(),(x).end()
const double PI = acos(-1);
const ll MOD = 1000000007;
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}
 
template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}
///////////////////////////////////////////////////////////////

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); //入出力高速化
	while (true) {
	int H,W; cin >> W >> H;
	if (H == 0 && W == 0) break;
	vector<vector<int>> wallh(H, vector<int>(W-1)), wallw(H-1, vector<int>(W));
	rep(i,2*H-1) {
		if (i % 2 == 0) {
			rep(j,W-1) cin >> wallh[i/2][j];
		} else {
			rep(j,W) cin >> wallw[i/2][j];
		}
	}

	vector<vector<int>> d(H, vector<int>(W,INF));
	d[0][0] = 1;
	queue<pair<int, int>> que;
	que.emplace(make_pair(0,0));
    while (!que.empty()) {
        int y,x;
	    tie(y,x) = que.front(); que.pop();
	    if (x < W-1) {  
	        if (wallh[y][x] == 0 && d[y][x+1] == INF) {
			    que.emplace(make_pair(y,x+1));
			    d[y][x+1] = d[y][x] + 1;
		    } 
	    }
		if (x > 0) {  
	        if (wallh[y][x-1] == 0 && d[y][x-1] == INF) {
			    que.emplace(make_pair(y,x-1));
			    d[y][x-1] = d[y][x] + 1;
		    } 
	    }
		if (y < H-1) {  
	        if (wallw[y][x] == 0 && d[y+1][x] == INF) {
			    que.emplace(make_pair(y+1,x));
			    d[y+1][x] = d[y][x] + 1;
		    } 
	    }
		if (y > 0) {  
	        if (wallw[y-1][x] == 0 && d[y-1][x] == INF) {
			    que.emplace(make_pair(y-1,x));
			    d[y-1][x] = d[y][x] + 1;
		    } 
	    }
	}

	if (d[H-1][W-1] == INF) cout << 0 << endl;
	else cout << d[H-1][W-1] << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define pb(a) push_back(a)
#define rd(a) cin>>(a)
#define RD(a,b) cin>>(a)>>(b)
#define pr(a) cout<<(a)<<endl
#define PR(a,b) cout<<(a)<<" "<<(b)<<endl
#define F first
#define S second
#define ll long long
bool check(int n,int m,int x,int y){return (x<0||x>=n||y<0||y>=m)?false:true;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
typedef pair<int,int> P;

int main() {
  int n,m;
  while(RD(m,n) && (n||m)) { 
    vector<P> v[n][m];
    rep(i,n*2-1) {
      if(!(i%2)) {
	int k=m-1,x;
	rep(j,k) {
	  cin >> x;
	  if(!x) {
	    v[i/2][j].pb(P(i/2,j+1));
	    v[i/2][j+1].pb(P(i/2,j));
	  }
	}
      } else {
	int k=m,x;
	rep(j,k) {
	  cin >> x;
	  if(!x) {
	    v[i/2][j].pb(P(i/2+1,j));
	    v[i/2+1][j].pb(P(i/2,j));
	  }
	}
      }
    }
    int d[n][m];
    memset(d,0,sizeof(d));
    d[0][0]=1;
    queue<P> que;
    que.push(P(0,0));
    while(!que.empty()) {
      P p=que.front();que.pop();
      int nx=p.F,ny=p.S;
      rep(i,v[nx][ny].size()) {
	P q=v[nx][ny][i];
	int x=q.F,y=q.S;
	if(!d[x][y]) {
	  d[x][y]=d[nx][ny]+1;
	  que.push(P(x,y));
	}
      }
    }
    pr(d[n-1][m-1]);
  }
  return 0;
}