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(int i = 0;i<n;i++)
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0;}

const int dx[4] = {-1,1,0,0};
const int dy[4] = {0,0,-1,1};
const int INF = 1001001001;
int main() {
    int w,h;
    while(1) {
        cin >> w >> h;
        if(w == 0 && h == 0) break;
            bool board[50][50][4];
            rep(i,h) rep(j,w) rep(k,4) board[i][j][k] = true;

            rep(i,w) board[0][i][0] = false; // up
            rep(i,w) board[h-1][i][1] = false; // down
            rep(i,h) board[i][0][2] = false; //left
            rep(i,h) board[i][w-1][3] = false; // right

            rep(i,2*h-1) {
                if(i%2 == 0) {
                    rep(j,w-1) {
                        int a;
                        cin >> a;
                        if(a == 1) {
                            board[i/2][j][3] = false;
                            board[i/2][j+1][2] = false;
                        }
                    }
                } else {
                    rep(j,w) {
                        int a;
                        cin >> a;
                        if(a==1) {
                            board[i/2][j][1] = false;
                            board[i/2+1][j][0] = false;
                        }
                    }
                }
            }
            queue<P>q;
            q.push({0,0});
            int dist[50][50];
            rep(i,h) rep(j,w) dist[i][j] = INF;
            dist[0][0] = 1;
            while(!q.empty()) {
                P p = q.front();q.pop();
                int x, y;
                x = p.first; y = p.second;
                rep(i,4) {
                    int nx = x + dx[i];
                    int ny = y + dy[i];
                    if(!board[x][y][i]) continue;
                    if(dist[nx][ny] == INF) {
                        dist[nx][ny] = dist[x][y] + 1;
                        q.push({nx,ny});
                    } 
                }
            }
            if(dist[h-1][w-1] == INF) cout << 0 << endl;
            else cout << dist[h-1][w-1] << endl;
    }        
}

C++: #include <iostream>
#include <algorithm>
#include <queue>
#include <map>
#define L 2
#define U 3
#define R 0
#define D 1

using namespace std;
   
const int dx[4] = {-1,0,1,0};
const int dy[4] = {0,-1,0,1};
   
int cost[30][30];
bool wall[4][30][30];
bool visited[30][30];
int w, h;
   
int bfs(int sx, int sy, int gx, int gy) {
  fill(cost[0], cost[32], 0);
  fill(visited[0], visited[32], false);
  cost[0][0] = 1;
     
  queue<pair<int, int> > Q;
  Q.push(make_pair(0, 0));
  visited[0][0] = true;
  while(!Q.empty()) {
    pair<int, int> st = Q.front(); Q.pop();
       
    if(st.first == gx && st.second == gy) {
      return cost[gy][gx];
    }
       
    for(int i=0; i<4; i++) {
      int nx = st.first + dx[i]
	int ny = st.second + dy[i];
      if(0<= nx && nx < w && 0<= ny && ny < h) {
	if(!visited[ny][nx] && !wall[i][st.second][st.first]) {
	  visited[ny][nx] = true;
	  cost[ny][nx] = cost[st.second][st.first] + 1;
	  Q.push(make_pair(nx, ny));
	}
      }
    }
  }
  return 0;
}

int main(void) {
  while(cin >> w >> h && w+h) {
    fill(wall[0][0], wall[4][30], 0);
    
    for(int i=0; i<h; i++) {
      wall[R][i][0] = wall[L][i][w-1] = 1;
    }
    for(int i=0; i<w; i++) {
      wall[D][0][i] = wall[U][h-1][i] = 1;
    }
    
    for(int i=0; i<h; i++) {
      
      for(int j=0; j<w-1; j++) {
	cin >> wall[L][i][j];
	wall[R][i][j+1] = wall[L][i][j];
      }
      
      if(i < h-1) {
	for(int j=0; j<w; j++) {
	  cin >> wall[U][i][j];
	  wall[D][i+1][j] = wall[U][i][j];
	}
      }
    }
    cout << bfs(0, 0, w-1, h-1) << endl;
  }
   return 0;
}