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>
using namespace std;
#define REP(i,n) for (int i=0;i<(n);i++)
#define REP2(i,m,n) for (int i=m;i<(n);i++)

int B[100][100];
bool used[100][100];
int dr[4] = {-1, 1, 0, 0};
int dc[4] = {0, 0, -1, 1};

int solve() {
    int H, W;
    cin >> W >> H;
    cin.ignore();
    if (H == 0) return -1;

    H = H * 2 + 1;
    W = W * 2 + 1;

    REP(i, H) B[i][0] = B[i][W-1] = 1;
    REP(j, W) B[0][j] = B[H-1][j] = 1;
    
    REP2(i, 1, H-1) {
        string s;
        getline(cin, s);
        REP2(j, 1, W-1) {
            if (s[j-1] == '1') B[i][j] = 1;
            else B[i][j] = 0;
        }
    }

    REP(i, H) REP(j, W) used[i][j] = false;

    
    deque<tuple<int, int, int> > queue;
    queue.push_back(make_tuple(1, 1, 1));
    while(!queue.empty()) {
        int r, c, d;
        tie(r, c, d) = queue.front();
        queue.pop_front();
        if (r == H - 2 && c == W - 2) return d;
        if (used[r][c]) continue;
        used[r][c] = true;

        REP(i, 4) {
            int nr = r + dr[i];
            int nc = c + dc[i];
            if (nr < 0 || nr >= H || nc < 0 || nc >= W) continue;
            if (B[nr][nc] || used[nr][nc]) continue;
            nr = nr + dr[i];
            nc = nc + dc[i];
            if (nr < 0 || nr >= H || nc < 0 || nc >= W) continue;
            if (B[nr][nc] || used[nr][nc]) continue;
            
            queue.push_back(make_tuple(nr, nc, d+1));
        }
    }

    return 0;
}

int main() {
    while (true) {
        int ret = solve();
        if (ret == -1) break;
        cout << ret << endl;
    }
}

C++: #include <cstdio>
#include <cstdint>
#include <vector>
#include <queue>
#include <algorithm>
#include <utility>
#include <tuple>

static size_t const m1 = -1;
static size_t const di[] = {m1, 0, 1, 0};
static size_t const dj[] = {0, m1, 0, 1};

int testcase_ends() {
  size_t h, w;
  scanf("%zu %zu", &w, &h);
  if (h == 0 && w == 0) return 1;

  std::vector<std::vector<int>> s(h+h-1);
  for (size_t i = 0; i < h+h-1; ++i) {
    if (i % 2 == 0) {
      s[i].resize(w-1);
      for (auto& sij: s[i]) scanf("%d", &sij);
    } else {
      s[i].resize(w);
      for (auto& sij: s[i]) scanf("%d", &sij);
    }
  }

  int inf = h*w;
  std::vector<std::vector<int>> dp(h, std::vector<int>(w, inf));
  dp[0][0] = 1;
  std::queue<std::pair<size_t, size_t>> q;
  q.emplace(0, 0);
  while (!q.empty()) {
    size_t i, j;
    std::tie(i, j) = q.front();
    q.pop();
    for (size_t k = 0; k < 4; ++k) {
      size_t ni = i + di[k];
      size_t nj = j + dj[k];
      if (!(ni < h && nj < w)) continue;
      if (s[i+ni][(j+nj)/2]) continue;
      if (!(dp[ni][nj] > dp[i][j] + 1)) continue;

      dp[ni][nj] = dp[i][j] + 1;
      q.emplace(ni, nj);
    }
  }
  if (dp[h-1][w-1] == inf) return puts("0"), 0;
  printf("%d\n", dp[h-1][w-1]);
  return 0;
}

int main() {
  while (!testcase_ends()) {}
}