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 <array>
#include <cstdint>
#include <iostream>
#include <vector>

using namespace std;
void dfs(array<array<uint32_t, 30>, 30> &maze, int32_t h, int32_t w,
         vector<vector<uint32_t>> &vwalls, vector<vector<uint32_t>> &pwalls,
         uint32_t depth) {
  // cerr << h << " " << w << " " << depth << endl;
  maze[h][w] = depth;
  if (pwalls[h][w] == 0 && maze[h][w + 1] == 0) {
    dfs(maze, h, w + 1, vwalls, pwalls, depth + 1);
  }
  if (h - 1 > 0 && vwalls[h - 1][w] == 0 && 0 == maze[h - 1][w]) {
    dfs(maze, h - 1, w, vwalls, pwalls, depth + 1);
  }
  if (vwalls[h][w] == 0 && 0 == maze[h + 1][w]) {
    dfs(maze, h + 1, w, vwalls, pwalls, depth + 1);
  }
  if (w - 1 > 0 && pwalls[h][w - 1] == 0 && 0 == maze[h][w - 1]) {
    dfs(maze, h, w - 1, vwalls, pwalls, depth + 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);

    dfs(maze, 0, 0, vwalls, pwalls, 1);

    cout << maze[h - 1][w - 1] << endl;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

// 総数を1000000007（素数）で割った余り
const long long mod = 1e9 + 7;

using ll = long long;
using pii  = pair<int, int>;
using pll = pair<ll, ll>;
#define ull unsigned long long
#define ld long double
#define vi vector<int>
#define vll vector<ll>
#define vc vector<char>
#define vs vector<string>
#define vpii vector<pii>
#define vpll vector<pll>

#define rep(i, n) for (int i = 0, i##_len = (n); i < i##_len; i++)
#define rep1(i, n) for (int i = 1, i##_len = (n); i <= i##_len; i++)
#define repr(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rep1r(i, n) for (int i = ((int)(n)); i >= 1; i--)

#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define RSORT(x) sort(rall(x));
#define pb push_back
#define mp make_pair

#define INF (1e9)
#define PI (acos(-1))
#define EPS (1e-7)

ull gcd(ull a, ull b) { return b ? gcd(b, a % b) : a; }
ull lcm(ull a, ull b) { return a / gcd(a, b) * b; }

int main(){
    while (1) {
        int w, h;
        cin >> w >> h;
        if (w==0 && h==0) break;
        vs wall(2*h-1);
        cin.ignore();
        rep(i, sz(wall)) getline(cin, wall[i]);
        vector<vi> dist(h, vi(w, INF));
        auto bfs = [&] () {
            dist[0][0] = 1;
            int d = 1;
            bool flug = true;
            while (flug) {
                flug = false;
                rep(y, h) rep(x, w) {
                    if (dist[y][x] != d) continue;
                    const vi dy = { -1, 0, 1, 0 }, dx = { 0, 1, 0, -1 };
                    rep(i, 4) {
                        int ny = y + dy[i], nx = x + dx[i];
                        if (ny<0 || ny>=h || nx<0 || nx>=w) continue;
                        if (wall[y+ny][x+nx]=='1') continue;
                        if (dist[ny][nx]!=INF) continue;
                        dist[ny][nx] = d + 1;
                        if (ny==h-1 && nx==w-1) return;
                        flug = true;
                    }
                }
                ++d;
            }
        };
        bfs();
        int ans = dist[h-1][w-1];
        if (ans==INF) ans = 0;
        cout << ans << endl;
    }
    return 0;
}