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, a) for (int i = 0; i < (int) (a); i++)
#define reps(i, a, b) for (int i = (int) (a); i < (int) (b); i++)
#define rrep(i, a) for (int i = (int) a-1; i >= 0; i--)
#define rreps(i, a, b) for (int i = (int) (a)-1; i >= (int) (b); i--)
#define MP(a, b) make_pair((a), (b))
#define PB(a) push_back((a))
#define all(v) (v).begin(), (v).end()
#define PRINT(f) if((f)){cout << (TRUE__) << endl;}else{cout << FALSE__ << endl;}
#define TRUE__ "YES"
#define FALSE__ "NO"
#define PERM(v) next_permutation(all(v))
#define UNIQUE(v) sort(all(v));(v).erase(unique(all(v)), v.end())
#define CIN(type, x) type x;cin >> x

#ifdef LOCAL
#define lcout(a) cout << a;
#define lcoutln(a) cout << a << endl;
#define lcerr(a) cerr << a;
#define lcerrln(a) cerr << a << endl;
#else
#define lcout(a) 
#define lcoutln(a) 
#define lcerr(a) 
#define lcerrln(a) 
#endif

#define INF 1e9

int W, H;
int cost[30][30];
bool wall[30][30][4];

void init()
{
	rep(i, 30) rep(j, 30) {
		cost[i][j] = INF;
		rep(k, 4) wall[i][j][k] = true;
	}
}

int main()
{
	cin >> W >> H;
	while (W) {
		init();
		rep(i, W-1) {
			CIN(int, t);
			if (t == 0) {
				wall[0][i][1] = wall[0][i+1][3] = false;
			}
		}
		reps(i, 1, H) {
			rep(j, W) {
				CIN(int, t);
				if (t == 0) {
					wall[i][j][0] = wall[i-1][j][2] = false;
				}
			}
			rep(j, W-1) {
				CIN(int, t);
				if (t == 0) {
					wall[i][j][1] = wall[i][j+1][3] = false;
				}
			}
		}
		cost[0][0] = 1;
		queue<pair<int, int> > q;
		q.push(MP(0, 0));
		while(!q.empty()) {
			auto p = q.front();
			int r = p.first;
			int c = p.second;
			int dr[] = {-1, 0, 1, 0};
			int dc[] = { 0, 1, 0,-1};
			rep(i, 4) {
				int nr = r+dr[i];
				int nc = c+dc[i];
				if (cost[nr][nc] == INF && !wall[r][c][i]) {
					cost[nr][nc] = cost[r][c] + 1;
					q.push(MP(nr, nc));
				}
			}
			q.pop();
		}
		if (cost[H-1][W-1] == INF) cout << 0 << endl;
		else cout << cost[H-1][W-1] << endl;
		cin >> W >> H;
	}
}

C++: #define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <utility>
#include <stack>
#include <vector>
#include <queue>
#include <algorithm>
#include <map>
#include <climits>
#include <set>
#include <cmath>
#include <numeric>
#include <iomanip>

using namespace std;
int side_walls[30][30];
int down_walls[30][30];
int d[30][30];
int main(void){
  int w;
  int h;
  while(true){
    cin >> w >> h;
    if(w == 0 && h == 0){
      break;
    }
    for(int i = 0; i < 2 * h - 1; i++){
      if(i % 2 == 0){
        for(int j = 0; j < w - 1; j++){
          cin >> side_walls[i / 2][j];
        }
      } else {
        for(int j = 0; j < w; j++){
          cin >> down_walls[i / 2][j];
        }
      }
    }

    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++){
        d[i][j] = INT_MAX;
      }
    }

    queue <pair <int, int> > q;
    d[0][0] = 1;
    q.push(make_pair(0, 0));
    while(!q.empty()){
      int cur_h = q.front().first;
      int cur_w = q.front().second;
      q.pop();
      int next_d = d[cur_h][cur_w] + 1;
      if(cur_h > 0 && down_walls[cur_h - 1][cur_w] == 0 && d[cur_h - 1][cur_w] == INT_MAX){
        d[cur_h - 1][cur_w] = next_d;
        q.push(make_pair(cur_h - 1, cur_w));
      }
      if(cur_h < h - 1 && down_walls[cur_h][cur_w] == 0 && d[cur_h + 1][cur_w] == INT_MAX){
        d[cur_h + 1][cur_w] = next_d;
        q.push(make_pair(cur_h + 1, cur_w));
      }
      if(cur_w > 0 && side_walls[cur_h][cur_w - 1] == 0 && d[cur_h][cur_w - 1] == INT_MAX){
        d[cur_h][cur_w - 1] = next_d;
        q.push(make_pair(cur_h, cur_w - 1));
      }
      if(cur_w < w - 1 && side_walls[cur_h][cur_w] == 0 && d[cur_h][cur_w + 1] == INT_MAX){
        d[cur_h][cur_w + 1] = next_d;
        q.push(make_pair(cur_h, cur_w + 1));
      }
    }

    if(d[h - 1][w - 1] == INT_MAX){
      cout << 0 << endl;
    } else {
      cout << d[h - 1][w - 1] << endl;
    }
  }
  return 0;
}