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>
 
#define rep(i,n) for(ll i=0;i<n;++i)
#define ALL(a) (a).begin(),(a).end()
 
using namespace std;
using ll  = long long;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
 
const ll MOD  = 1e9+7;
const ll LINF = 1LL << 60;
const int INF = 1e9 + 7;

int mvx[]={0, 0, -1, 1};
int mvy[]={-1, 1, 0, 0};
string ms[] = {"up", "down", "left", "right"};


int main(){
    int h, w;
    while(cin >> w >> h, h || w){
        //上下左右に動けるか
        bool maize[h][w][4] = {};

        rep(i, 2*h-1){
            int inp;

            if(i&1){
                rep(j, w){
                    cin >> inp;
                    if(inp == 0){
                        maize[i/2][j][1] = true;
                        maize[i/2+1][j][0] = true;
                    }
                }
            }
            else{
                rep(j, w-1){
                    cin >> inp;
                    if(inp == 0){
                        maize[i/2][j][3] = true;
                        maize[i/2][j+1][2] = true;
                    }
                }
            }
        }

        int dist[h][w];
        rep(i, h)rep(j, w)dist[i][j] = INF;
        dist[0][0] = 1;

        bool visited[h][w] = {};
        visited[0][0] = true;
        
        queue<pll> que;
        que.push(make_pair(0, 0));

        while(!que.empty()){
            pll pos = que.front();
            que.pop();

            if(pos.first == h-1 && pos.second == w-1)break;
            
            rep(i, 4){
                if(!maize[pos.first][pos.second][i])continue;

                int dx = pos.second + mvx[i];
                int dy = pos.first + mvy[i];

                if(dy < 0 || dy >= h || dx < 0 || dx >= w)continue;

                if(visited[dy][dx])continue;
                visited[dy][dx] = true;

                

                dist[dy][dx] = dist[pos.first][pos.second] + 1;
                que.push(make_pair(dy, dx));
            }
        }

        if(dist[h-1][w-1] >= INF)cout << 0 << endl;
        else cout << dist[h-1][w-1] << endl;
    }
}

C++: #include <map>
#include <set>
#include <cmath>
#include <queue>
#include <stack>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>

#define INF (2 << 28)
#define fr first
#define sc second
using namespace std;

typedef pair< int, int > iP;
typedef pair< iP, int > iiP;

int W, H;
bool edge[33][33][33][33];

int bfs() {
  static int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
  vector< vector< int > > used(H + 1, vector< int >(W + 1, INF));
  queue< iP > que;
  used[0][0] = 0;
  que.push(iP(0, 0));
  while(!que.empty()) {
    iP p = que.front(); que.pop();
    for(int i = 0; i < 4; i++) {
      int nx = p.fr + dx[i], ny = p.sc + dy[i];
      if(edge[p.sc][p.fr][ny][nx] && 0 <= nx && nx < W && 0 <= ny && ny < H && used[p.sc][p.fr] + 1 < used[ny][nx]) {
        que.push(iP(nx, ny));
        used[ny][nx] = used[p.sc][p.fr] + 1;
      }
    } 
  }
  return (used[H - 1][W - 1] == INF ? 0 : used[H - 1][W - 1] + 1);
}

int main(){
  
  while(cin >> W >> H, W) {
    memset(edge, true, sizeof(edge));
    for(int i = 0; i < H * 2 - 1; i++) {
      if(i % 2 == 0) {
        for(int j = 0; j < W - 1; j++) {
          int mas; cin >> mas;
          if(mas) edge[i / 2][j][i / 2][j + 1] = edge[i / 2][j + 1][i / 2][j] = false;
        }
      }
      else {
        for(int j = 0; j < W; j++) {
          int mas; cin >> mas;
          if(mas) edge[i / 2][j][i / 2 + 1][j] = edge[i / 2 + 1][j][i / 2][j] = false;
        }
      }
    }
    
    cout << bfs() << endl;
  }
}