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;
const ll MOD = 1e9 + 7;
const ll INF = 1LL << 60;
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define debug(x) cerr << #x << ": " << x << endl;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

int main() {
    ll w, h;
    while(cin >> w >> h) {
        if (w == 0 && h == 0) return 0;

        vector<vector<ll>> bh(h, vector<ll>(w-1)), bw(h-1, vector<ll>(w));
        rep(i, h-1) {
            rep(j, w-1) cin >> bh[i][j];
            rep(j, w) cin >> bw[i][j];
        }
        rep(j, w-1) cin >> bh[h-1][j];

        vector<vector<ll>> dist(h, vector<ll>(w, 0));
        dist[0][0] = 1;
        queue<pair<ll, ll>> que;
        que.emplace(0, 0);
        ll dx[4] = {0, 0, 1, -1}, dy[4] = {1, -1, 0, 0};

        while(!que.empty()) {
            ll x = que.front().second, y = que.front().first;
            que.pop();

            rep(i, 4) {
                ll nx = x + dx[i], ny = y + dy[i];
                if (nx < 0 || w <= nx || ny < 0 || h <= ny || dist[ny][nx] != 0) continue;
                else if (i == 0 && bw[y][x] == 1) continue;
                else if (i == 1 && bw[y-1][x] == 1) continue;
                else if (i == 2 && bh[y][x] == 1) continue;
                else if (i == 3 && bh[y][x-1] == 1) continue;

                dist[ny][nx] = dist[y][x] + 1;
                que.emplace(ny, nx);
            }
        }
        cout << dist[h-1][w-1] << endl;
    }

}

C++: #define _USE_MATH_DEFINES
#define INF 100000000

#include <iostream>
#include <sstream>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>
#include <cctype>
#include <utility>

using namespace std;

typedef long long ll;
typedef pair <int,int> P;
typedef pair <int,P> PP;

static const double EPS = 1e-8;

int tx[] = {0,1,0,-1};
int ty[] = {-1,0,1,0};

int cost[30][30][30][30];
int visited[30][30];
int W,H;

int main()
{
	while(~scanf("%d %d",&W,&H)){
		if(W==H && H==0) break;
		memset(cost,0,sizeof(cost));
		memset(visited,0x3f,sizeof(visited));

		for(int y=0;y<2*H-1;y++){
			if(y%2==0){
				for(int x=0;x<W-1;x++){
					int n;
					scanf("%d",&n);
					cost[y/2][x][y/2][x+1] = n;
					cost[y/2][x+1][y/2][x] = n;
				}
			}
			else{
				for(int x=0;x<W;x++){
					int n;
					scanf("%d",&n);
					cost[y/2][x][y/2+1][x] = n;
					cost[y/2+1][x][y/2][x] = n;
				}
			}
		}

		priority_queue<PP,vector<PP>,greater<PP> > que;
		que.push(PP(0,P(0,0)));

		visited[0][0] = 0;
		while(!que.empty()){
			int d = que.top().first;
			int x = que.top().second.first;
			int y = que.top().second.second;
			que.pop();

			for(int i=0;i<4;i++){
				int dx = x + tx[i];
				int dy = y + ty[i];
				if(dx < 0 || dx >= W || dy < 0 || dy >= H) continue;
				if(cost[y][x][dy][dx]==1) continue;
				if(visited[dy][dx] <= d+1) continue;

				visited[dy][dx] = d+1;
				que.push(PP(d+1,P(dx,dy)));
			}
		}

		printf("%d\n",visited[H-1][W-1] == 0x3f3f3f3f ? 0 : visited[H-1][W-1] + 1);
	}
}