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>
#ifdef _DEBUG
#include "debug.hpp"
#else
#define debug(...)
#endif
#define REP(i, m, n) for(int (i) = (m); (i) < (n); ++i)
#define rep(i, n) REP(i, 0, n)
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
const int INF = 1e9 + 7;
const ll LINF = 1LL << 60;
template<class T, class U> inline bool chmax(T &a, const U &b) { if(a < b) { a = b; return true; } return false; }
template<class T, class U> inline bool chmin(T &a, const U &b) { if(a > b) { a = b; return true; } return false; }

int w, h;
vector<int> dx = {1, 0, -1, 0};
vector<int> dy = {0, 1, 0, -1};

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  for(;;) {
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    vector<vector<vector<P>>> g(h, vector<vector<P>>(w));
    rep(i,2*h-1) {
      if(i%2) {
        rep(j,w) {
          int c;
          cin >> c;
          if(!c) g[i/2][j].push_back({i/2+1, j}), g[i/2+1][j].push_back({i/2, j});
        }
      }
      else {
        REP(j,1,w) {
          int c;
          cin >> c;
          if(!c) g[i/2][j-1].push_back({i/2, j}), g[i/2][j].push_back({i/2, j-1});
        }
      }
    }
    queue<P> q;
    q.push({0, 0});
    vector<vector<int>> dst(h, vector<int>(w, -1));
    dst[0][0] = 0;
    while(!q.empty()) {
      int y = q.front().first, x = q.front().second; q.pop();
      for(P v : g[y][x]) {
        int ny = v.first, nx = v.second;
        if(ny < 0 || h <= ny || nx < 0 || w <= nx || dst[ny][nx] != -1) continue;
        dst[ny][nx] = dst[y][x]+1;
        q.push({ny, nx});
      }
    }
    int ans = dst[h-1][w-1]+1;
    cout << ans << '\n';
  }
  return 0;
}

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

const int INF = 1e+9;
typedef pair<int, int> P;

int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, -1, 1};
int h, w;
int maze[256][128];

bool check(int x, int y){
	return x >= 0 && x < w && y >= 0 && y < h * 2 - 1 && maze[y][x] == 0;
}
int main() {
	
	while(cin >> w >> h && (w || h)){
		memset(maze, 0, sizeof(maze));
		for(int i = 0; i < h * 2 - 1; ++i){
			if(i % 2){
				for(int j = 0; j < w; ++j){
					scanf("%d", &maze[i][j]);
				}
			}
			else{
				for(int j = 1; j < w; ++j){
					scanf("%d", &maze[i][j]);
				}		
			}
		}
		int d[128][128];
		for(int i = 0; i < 128; ++i)
			for(int j = 0; j < 128; ++j)
				d[i][j] = INF;
		
		int ans = 0;
		queue<P> que;
		que.push(P(0, 0));
		d[0][0] = 0;
		while(!que.empty()){
			P p = que.front();
			que.pop();
			if(p.first == w - 1 && p.second == h - 1){
				ans = d[h - 1][w - 1] + 1;
				break;
			}
			for(int i = 0; i < 2; ++i){
				int nx = p.first + dx[i];
				int ny = p.second + dy[i];
				if(check(nx, ny * 2) && d[ny][nx] == INF){
					d[ny][nx] = d[p.second][p.first] + 1;
					que.push(P(nx, ny));
				}
			}
			for(int i = 2; i < 4; ++i){
				int nx = p.first + dx[i];
				int ny = p.second + dy[i];
				if(i == 2 && check(nx, ny * 2 + 1) && d[ny][nx] == INF){
					d[ny][nx] = d[p.second][p.first] + 1;
					que.push(P(nx, ny));
				}
				else if(i == 3 && check(nx, ny * 2 - 1) && d[ny][nx] == INF){
					d[ny][nx] = d[p.second][p.first] + 1;
					que.push(P(nx, ny));
				}
			}
		}
		cout << ans << endl;
	}
	
	return 0;
}