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 <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;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define inf (int)(1e9)

int main(){
  while(1){
    int H, W, i, j, kabe;
    scanf("%d%d", &W, &H);
    if(H == 0 && W == 0){
      return 0;
    }
    vector<vector<int>> D(H, vector<int>(W, inf));
    vector<vector<vector<int>>> can_go(H, vector<vector<int>>(W, vector<int>(4, 0)));
    for(i = 0; i < 2 * H - 1; i++){
      if(i % 2 == 0){
        for(j = 0; j < W - 1; j++){
          scanf("%d", &kabe);
          if(kabe == 0){
    //        printf("(%d, %d, %d)\n", i / 2, j, 1);
    //        printf("(%d, %d, %d)\n", i / 2, j + 1, 3);
            can_go[i / 2][j][1] = 1;
            can_go[i / 2][j + 1][3] = 1;
          }
        }
      }
      else{
        for(j = 0; j < W; j++){
          scanf("%d", &kabe);
          if(kabe == 0){
    //        printf("(%d, %d, %d)\n", i / 2, j, 2);
    //        printf("(%d, %d, %d)\n", i / 2 + 1, j, 0);
            can_go[i / 2][j][2] = 1;
            can_go[i / 2 + 1][j][0] = 1;
          }
        }
      }
    }
    int dx[4] = {-1, 0, 1, 0};
    int dy[4] = {0, 1, 0, -1};
    queue<pair<pair<int, int>, int>> q;
    q.push(pair<pair<int, int>, int>(pair<int, int>(0, 0), 1));
    while(q.size() > 0){
      int x = q.front().first.first;
      int y = q.front().first.second;
      int v = q.front().second;
  //    printf("(x, y, v) = (%d, %d, %d)\n", x, y, v);
      q.pop();
      if(x < 0 || H < x || y < 0 || W < y || D[x][y] <= v){
        continue;
      }
      D[x][y] = v;
      for(int d = 0; d < 4; d++){
        if(can_go[x][y][d] == 1){
  //        printf("go(%d)\n", d);
          q.push(pair<pair<int, int>, int>(pair<int, int>(x + dx[d], y + dy[d]), v + 1));
        }
      }
    }
  /*  for(i = 0; i < H; i++){
      for(j = 0; j < W; j++){
        printf("%d ", D[i][j]);
      }
      printf("\n");
    }
*/    if(D[H - 1][W - 1] >= inf){
      printf("0\n");
    }
    else{
      printf("%d\n", D[H - 1][W - 1]);
    }
  }
}