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 <vector>
#include <algorithm>
#include <queue>
#define N 30
#define MP make_pair
#define P pair<int, int>
using namespace std;

int v[N][N];
bool f[N][N];
int w, h;

int main()
{
	int x, y;
	while (cin >> w >> h, w) {
		fill((int*)v, (int*)(v+w), 0);
		fill((bool*)f, (bool*)(f+w), 0);

		for (int i = 0; i < w; i++) {
			v[i][0] |= 0b1000;
			v[i][h-1] |= 0b0100;
		}
		for (int i = 0; i < h; i++) {
			v[0][i] |= 0b0010;
			v[w-1][i] |= 0b0001;
		}
		for (int i = 0; i < h-1; i++) {
			for (int j = 0; j < w-1; j++) {
				cin >> x;
				v[j][i] |= x;
				x <<= 1;
				v[j+1][i] |= x;
			}
			for (int j = 0; j < w; j++) {
				cin >> x;
				x <<= 2;
				v[j][i] |= x;
				x <<= 1;
				v[j][i+1] |= x;
			}
		}
		for (int j = 0; j < w-1; j++) {
			cin >> x;
			v[j][h-1] |= x;
			x <<= 1;
			v[j+1][h-1] |= x;
		}
		int res = 0;
		queue<pair<pair<int, int>, int> > q;
		q.push(MP(MP(0,0),1));
		while (!q.empty()) {
			pair<pair<int, int>, int> a = q.front();
			q.pop();
			pair<int, int> xy = a.first;
			if (f[xy.first][xy.second]) continue;
			f[xy.first][xy.second] = 1;
			if (xy.first == w - 1 && xy.second == h - 1) {
				res = a.second;
				break;
			}
			if (!(v[xy.first][xy.second] & 0b1000))
				q.push(MP(MP(xy.first,xy.second-1), a.second+1));
			if (!(v[xy.first][xy.second] & 0b0100))
				q.push(MP(MP(xy.first,xy.second+1), a.second+1));
			if (!(v[xy.first][xy.second] & 0b0010))
				q.push(MP(MP(xy.first-1,xy.second), a.second+1));
			if (!(v[xy.first][xy.second] & 0b0001)) 
				q.push(MP(MP(xy.first+1,xy.second), a.second+1));
		}
		cout << res << endl;
	}
	return 0;
}

C++: #include <array>
#include <cstdint>
#include <iostream>
#include <queue>
#include <vector>

using namespace std;

void bfs(array<array<uint32_t, 30>, 30> &maze, vector<vector<uint32_t>> &vwalls,
         vector<vector<uint32_t>> &pwalls) {
  queue<pair<pair<int32_t, int32_t>, uint32_t>> q;

  q.push({{0, 0}, 1});

  while (!q.empty()) {
    pair<pair<int32_t, int32_t>, uint32_t> p = q.front();
    q.pop();
    int32_t h = p.first.first;
    int32_t w = p.first.second;
    int32_t step = p.second;
    maze[h][w] = step;
    if (pwalls[h][w] == 0 && maze[h][w + 1] == 0) {
      q.push({{h, w + 1}, step + 1});
    }
    if (vwalls[h][w] == 0 && maze[h + 1][w] == 0) {
      q.push({{h + 1, w}, step + 1});
    }
    if (h - 1 > 0 && vwalls[h - 1][w] == 0 && maze[h - 1][w] == 0) {
      q.push({{h - 1, w}, step + 1});
    }
    if (w - 1 > 0 && pwalls[h][w - 1] == 0 && maze[h][w - 1] == 0) {
      q.push({{h, w - 1}, step + 1});
    }
  }
}

int32_t main() {
  while (true) {
    int32_t w, h;
    cin >> w >> h;
    if (w == 0) break;

    array<array<uint32_t, 30>, 30> maze{{0}};

    vector<vector<uint32_t>> vwalls;
    vector<vector<uint32_t>> pwalls;

    for (uint32_t i = 0; i < 2 * h - 1; i++) {
      uint32_t block;
      if (i % 2 == 0) {
        vector<uint32_t> walls;
        for (uint32_t j = 0; j < w - 1; j++) {
          cin >> block;
          walls.push_back(block);
        }
        walls.push_back(1);
        pwalls.push_back(walls);
      } else {
        vector<uint32_t> walls;
        for (uint32_t j = 0; j < w; j++) {
          cin >> block;
          walls.push_back(block);
        }
        vwalls.push_back(walls);
      }
    }

    vector<uint32_t> senti;
    for (uint32_t j = 0; j < w; j++) {
      senti.push_back(1);
    }
    vwalls.push_back(senti);

    bfs(maze, vwalls, pwalls);

    if (maze[h - 1][w - 1] == UINT32_MAX) {
      cout << 0 << endl;
    } else {
      cout << maze[h - 1][w - 1] << endl;
    }
  }

  return 0;
}