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;
using ll=long long;
using ld=long double;

#define rep(i,N) for(int i=0;i<(int)(N);++i)
#define rrep(i,N) for(int i=(int)(N)-1;i>=0;--i)
#define debug(x) cout<<#x<<"="<<x<<endl;
constexpr ll MOD=1000000007;
constexpr ll INF=1LL<<60;
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return true;}return false;}
template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return true;}return false;}
template<typename T> void fail(T v){cout << v << endl;exit(0);}
//template end
int W,H;
const int ma=1<<20;
int Id(int h,int w){return h*W+w;}
void solve(){
    while((cin>>W>>H,W|H)){
        vector<vector<int>> g(H*W);
        rep(j,2*H-1){
            if(j%2){
                rep(i,W){
                    int a;cin>>a;
                    if(!a){
                        g[Id(j/2,i)].push_back(Id(j/2+1,i));
                        g[Id(j/2+1,i)].push_back(Id(j/2,i));
                    }
                }
            }else{
                rep(i,W-1){
                    int a;cin>>a;
                    if(!a){g[Id(j/2,i)].push_back(Id(j/2,i+1));g[Id(j/2,i+1)].push_back(Id(j/2,i));}
                }
            }
        }
        queue<int> q;
        vector<int> dist(W*H,ma);
        dist[0]=1;
        q.push(0);
        while(q.size()){
            int p=q.front();q.pop();
            for(int e:g[p])
                if(dist[e]==ma){
                    dist[e]=dist[p]+1;q.push(e);
                }
        }
        if(dist[H*W-1]==ma)cout<<0<<endl;
        else cout<<dist[H*W-1]<<endl;
    }
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    solve();
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <utility>
using namespace std;

#define INF 10000000

struct pa {
	int first, second;
	pa(int a, int b) {
		first = a; second = b;
	}
};

bool operator<(pa a, pa b) {
	if(a.first != b.first)
		return a.first > b.first;
	else
		return a.second > b.second;
}

int main() {
	int w, h;

	while(cin >> w >> h, w || h) {
		cin.ignore();
		vector<string> v;
		for(int i = 0; i < h * 2 - 1; i++) {
			string str;
			getline(cin, str);
			str += "   ";
			v.push_back(str);
		}
		/* table */
		int table[32 * 32][32 * 32];
		bool visited[32 * 32];
		for(int i = 0; i < 32 * 32; i++) {
			for(int j = 0; j < 32 * 32; j++) {
				table[i][j] = INF;
			}
			table[i][i] = 0;
			visited[i] = false;
		}
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				if(i > 0)
					table[w * i + j][w * (i - 1) + j] = table[w * (i - 1) + j][w * i + j] = v[i * 2 - 1][j * 2] == '1' ? INF : 1;
				if(i < h - 1)
					table[w * i + j][w * (i + 1) + j] = table[w * (i + 1) + j][w * i + j] = v[i * 2 + 1][j * 2] == '1' ? INF : 1;
				if(j > 0)
					table[w * i + j][w * i + j - 1] = table[w * i + j - 1][w * i + j] = v[i * 2][j * 2 - 1] == '1' ? INF : 1;
				if(j < w - 1)
					table[w * i + j][w * i + j + 1] = table[w * i + j + 1][w * i + j] = v[i * 2][j * 2 + 1] == '1' ? INF : 1;
			}
		}

		priority_queue<pa> q;
		q.push(pa(0, 0));
		bool flag = true;
		while(!q.empty()) {
			pa tmp(0,0);
			tmp = q.top(); q.pop();
			if(visited[tmp.second])
				continue;
			visited[tmp.second] = true;

			if(tmp.second == h * w - 1) {
				if(tmp.first >= INF) {
					break;
				}
				flag = false;
				cout << tmp.first + 1 << endl;
			}
			if(tmp.second / w > 0) q.push(pa(tmp.first + table[tmp.second][tmp.second - w], tmp.second - w));
			if(tmp.second / w < h - 1) q.push(pa(tmp.first + table[tmp.second][tmp.second + w], tmp.second + w));
			if(tmp.second % w > 0) q.push(pa(tmp.first + table[tmp.second][tmp.second - 1], tmp.second - 1));
			if(tmp.second % w < w - 1) q.push(pa(tmp.first + table[tmp.second][tmp.second + 1], tmp.second + 1));
		}

		if(flag) {
			cout << 0 << endl;
		}
	}
}