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 <algorithm>
#include <iostream>
#include <math.h>
#include <stdio.h>
#include <string>
#include <sstream>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <cmath>
#include <queue>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
using namespace std;
typedef unsigned long long ll;

#define MAX_N 30

int maze[MAX_N][MAX_N];
int verticalWall[MAX_N][MAX_N];
int horizontalWall[MAX_N][MAX_N];

void init(){
	rep(i,MAX_N){
		rep(j,MAX_N){
			maze[i][j] = -1;
			verticalWall[i][j] = 0;
			horizontalWall[i][j] = 0;
		}
	}
}

struct node{
	int h;
	int w;
	int time;
};

int main()
{
	int h,w;
	cin>>w>>h;
	while( !(h == 0 && w == 0)){
		init();
		for(int i = 0; i != (2*h - 1); i++){
			if(i % 2 == 0){
				rep(j,(w-1)){
					cin>>verticalWall[i/2][j];
				}
			}else{
				rep(j,w){
					cin>>horizontalWall[(i-1)/2][j];
				}
			}
		}
		struct node now;
		now.h = 0;
		now.w = 0;
		now.time = 0;
		queue<struct node> que;
		que.push(now);
		maze[0][0] = 0;
		while( que.empty() != true){
			now = que.front();
			que.pop();
			int dh[4] = {-1,0,0,1};
			int dw[4] = {0,-1,1,0};
			rep(i,4){
				int nh = now.h + dh[i];
				int nw = now.w + dw[i];
				if( 0 <= nh && nh < h && 0 <= nw && nw < w){
					struct node next;
					if( i == 0 && horizontalWall[now.h - 1][now.w] == 0 && maze[nh][nw] == -1){
						next.h = nh;
						next.w = nw;
						next.time = now.time + 1;
						maze[nh][nw] = next.time;
						que.push(next);
					}else if( i == 3 && horizontalWall[now.h][now.w] == 0 && maze[nh][nw] == -1){
						next.h = nh;
						next.w = nw;
						next.time = now.time + 1;
						maze[nh][nw] = next.time;
						que.push(next);
					}else if( i == 1 && verticalWall[now.h][now.w-1] == 0 && maze[nh][nw] == -1){
						next.h = nh;
						next.w = nw;
						next.time = now.time + 1;
						maze[nh][nw] = next.time;
						que.push(next);
					}else if( i == 2 && verticalWall[now.h][now.w] == 0 && maze[nh][nw] == -1){
						next.h = nh;
						next.w = nw;
						next.time = now.time + 1;
						maze[nh][nw] = next.time;
						que.push(next);
					}
				}
				/*rep(i,h){
					rep(j,w) cout<<maze[i][j]<<" ";
					cout<<endl;
				}*/
			}
		}
		if(maze[h-1][w-1] == -1){
			cout<<0<<endl;
		}else{
			cout<<maze[h-1][w-1]+1<<endl;
		}
		cin>>w>>h;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

const int N = 33;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

void solve(int W, int H) {
    int wall[N][N][N][N];
    for(int i = 0; i < H; ++i) {
        for(int j = 0; j < W - 1; ++j) {
            cin >> wall[i][j][i][j + 1];
            wall[i][j + 1][i][j] = wall[i][j][i][j + 1];
        }
        if(i != H - 1) {
            for(int j = 0; j < W; ++j) {
                cin >> wall[i][j][i + 1][j];
                wall[i + 1][j][i][j] = wall[i][j][i + 1][j];
            }
        }
    }
    queue<pair<int, int>> que;
    vector<vector<int>> dist(H, vector<int>(W));
    que.emplace(0, 0);
    dist[0][0] = 1;
    while(!que.empty()) {
        auto cur = que.front(); que.pop();
        int y = cur.first, x = cur.second;
        for(int i = 0; i < 4; ++i) {
            int ny = y + dy[i], nx = x + dx[i];
            if(ny < 0 || nx < 0 || ny >= H || nx >= W) continue;
            if(dist[ny][nx]) continue;
            if(!wall[y][x][ny][nx]) {
                que.emplace(ny, nx);
                dist[ny][nx] = dist[y][x] + 1;
            }
        }
    }
    if(dist[H - 1][W - 1] == -1) cout << 0 << '\n';
    else cout << dist[H - 1][W - 1] << '\n';
}

int main() {
    int w, h;
    while(cin >> w >> h) {
        if(!w) break;
        solve(w, h);
    }
    return 0;
}