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 ll;
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep2(i,n) for(int i=1;i<=(n);i++)
#define rep3(i,i0,n) for(int i=i0;i<(n);i++)
#define pb push_back
#define mod 1000000007
#define INF 200000000000
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
ll gcd(ll a, ll b) {return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) {return a/gcd(a,b)*b;}
#define all(x) x.begin(), x.end()
#define mp make_pair
bool compare(pair<int, int> a, pair<int, int> b) {
    if(a.first != b.first){
        return a.first < b.first;
        
    }else{
        return a.second < b.second;
    }
}


bool In_map(ll y,ll x,ll h,ll w){
    if(y<0 || x<0 || y>=h || x>=w){
        return 0;
    }else{
        return 1;
    }
}
const vector<ll> dx{1,0,-1,0};
const vector<ll> dy{0,1,0,-1};
int main() {
    while(1){
        ll w,h;
        cin >>w>>h;
        if(w == 0 && h == 0){
            break;
        }
        
        map<tuple<ll, ll,ll ,ll>,bool> m;

        rep(i,h*2-1){
            rep(j,(i%2)?(w):(w-1)){
                bool tmp;
                cin >> tmp;
                if(i%2==0){
                    m[make_tuple(i/2,j,i/2,j+1)] = tmp;
                    m[make_tuple(i/2,j+1,i/2,j)] = tmp;
                }else{
                    m[make_tuple(i/2,j,i/2+1,j)] = tmp;
                    m[make_tuple(i/2+1,j,i/2,j)] = tmp;
                }
            }
        }
        
        vector<vector<ll> > dist(h,vector<ll>(w,-1));
        queue<pair<ll,ll> > que;
        dist[0][0] = 0;
        que.push(make_pair(0,0));
        ll flag=0;
        while(!que.empty()){
            pair<ll,ll> v = que.front();
            que.pop();
            if(v.first == h-1 && v.second == w-1 ){
                cout << dist[v.first][v.second]+1<<endl;
                flag = 1;
                break;
            }
            rep(dir,4){
                ll ny = v.first + dy[dir];
                ll nx = v.second + dx[dir];
                if(!In_map(ny,nx,h,w)) continue;
                //cout << "p1"<<endl;
                if(m[make_tuple(v.first,v.second,ny,nx)]) continue;
                //cout << "p2"<<endl;
                if(dist[ny][nx] != -1) continue;
                //cout << "p3"<<endl;
                dist[ny][nx] = dist[v.first][v.second] + 1;
                que.push(make_pair(ny,nx));
            }
        }
        if(flag == 0)
            cout << 0 << endl;
    }



    return 0;
    

}

C++: #include <iostream>
#include <queue>
#include <cstring>

using namespace std;

// →　↓　←　↑
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

class state {
public:
    int x, y, d;
    state(int a, int b, int c) { x = a; y = b; d = c; }
};

int main()
{
    int h, w;

    while (cin >> w >> h, w || h) {
        bool flag = false;
        bool maze[32][32][4];
        bool past[32][32];
        int inp;

        memset(maze, 0, sizeof(maze));
        memset(past, 0, sizeof(past));
        // Input
        for (int y = 0; y < h; y++) {
            for (int x = 0; x < w - 1; x++) {
                cin >> inp;
                if (inp == 0)
                    maze[y][x + 1][2] = maze[y][x][0] = false;
                else
                    maze[y][x + 1][2] = maze[y][x][0] = true;
            }

            if (y < h - 1) 
                for (int x = 0; x < w; x++) {
                    cin >> inp;
                    if (inp == 0)
                        maze[y + 1][x][3] = maze[y][x][1] = false;
                    else
                        maze[y + 1][x][3] = maze[y][x][1] = true;                        
                }
        }
        
        state s(0, 0, 1);
        queue<state> q;
        q.push(s);
        
        while (!q.empty()) {
            state now = q.front();
            q.pop();
            past[now.y][now.x] = true;
            
            if (now.x == w - 1 && now.y == h - 1) {
                cout << now.d << endl;
                flag = true;
                break;
            }

            for (int i = 0; i < 4; i++) {
                if (maze[now.y][now.x][i])
                    continue;
                int nx = now.x + dx[i];
                int ny = now.y + dy[i];

                if (nx < 0 || ny < 0 || nx >= w || ny >= h)
                    continue;

                if (past[ny][nx] == false)
                    q.push(state(nx, ny, now.d + 1));
            }
        }

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

    return 0;
}