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, s, n) for(int i = s; i < n; ++i)
#define rep(i, n)        REP(i, 0, n)
#define SORT(c)          sort((c).begin(), (c).end())
#define IINF    INT_MAX
#define LLINF LLONG_MAX
#define DEBUG false
  
typedef long long               ll;
typedef pair <int, int> ii;
  
/*
struct point{
    ll x;
    ll y;
    point(){x = 0;y = 0;}
    point(ll x, ll y):x(x), y(y){}
};
*/
 
int dw[] = {0, 1, 0 ,-1};
int dh[] = {1, 0 ,-1, 0};
 
int main() {
 
    int w, h;
    while(cin >> w >> h, w, h){
        vector<vector<int>> yoko(h ,vector<int>(w+1, 1));
        vector<vector<int>> tate(h+1 ,vector<int>(w, 1));
         
        rep(i, 2*h-1){
            if(i%2==0){
                rep(j, w-1) cin >> yoko[(int)(i/2)][j+1];
            }
            else{
                rep(j, w) cin >> tate[(int)(i/2)+1][j];
            }
        }
       
        queue<pair<ii, int>> qu;
        qu.push(make_pair(make_pair(0, 0), 0)); // h, w
         
        vector<vector<bool>> used(h, vector<bool>(w));
         
        int ans = 0;
         
        while(!qu.empty()){
            pair<ii, int> tmp = qu.front();
            qu.pop();
             
            int hh = tmp.first.first;
            int ww = tmp.first.second;
             
            if(used[hh][ww]) continue;
            used[hh][ww] = true;
            if(hh == h-1 && ww == w-1){
                ans = tmp.second + 1;
                break;
            }
             
            if(yoko[hh][ww] == 0) qu.push(make_pair(make_pair(hh, ww-1), tmp.second + 1));
            if(yoko[hh][ww+1] == 0) qu.push(make_pair(make_pair(hh, ww+1), tmp.second + 1));
            if(tate[hh][ww] == 0) qu.push(make_pair(make_pair(hh-1, ww), tmp.second + 1));
            if(tate[hh+1][ww] == 0) qu.push(make_pair(make_pair(hh+1, ww), tmp.second + 1));
        }
         
        cout << ans << endl;
 
    }
 
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <utility>
#include <queue>
using namespace std;

const int inf = 1000000009;

int in(int y, int x, int h, int w) {
    return 0 <= y && y < h && 0 <= x && x < w;
}

int main() {
    int w,h; 
    while (cin >> w >> h, (w!=0&&h!=0)) {
        vector<vector<int>> maze(h*2-1, vector<int>(w*2-1, inf));
        for (int i=0; i<(h*2-1); i++) {
            if (i%2 == 0) { // 横の壁
                for (int l=0; l<w-1; l++) {
                    int kabe; cin >> kabe;
                    maze[i][l*2+1] = -1 * kabe;
                }
            } else {        // 縦の壁
                for (int l=0; l<w; l++) {
                    int kabe; cin >> kabe;
                    maze[i][l*2] = -1 * kabe;
                }
            }
        }

        vector<int> ny = {1, 0, -1, 0};
        vector<int> nx = {0, -1, 0, 1};
        queue<pair<int, int>> q; q.push(make_pair(0, 0));
        maze[0][0] = 1;
        while (!q.empty()) {
            pair<int, int> cur=q.front(); q.pop();
            int cost = maze[cur.first][cur.second]+1;
            for (int i=0; i<4; i++) {
                int y = cur.first  + ny[i] + ny[i];
                int x = cur.second + nx[i] + nx[i];
                if ( in(y, x, h*2, w*2) 
                  && ((i%2==0&&maze[cur.first+ny[i]][cur.second]!=-1)
                    || (i%2==1&&maze[cur.first][cur.second+nx[i]]!=-1))
                  && cost < maze[y][x]) {
                    maze[y][x] = cost;
                    q.push(make_pair(y, x));
                }
            }
        }

        /*
        for (auto line: maze) {
            for (auto block: line) {
                if (block == -1) {
                    cout << "#";
                } else if (block == inf) {
                    cout << "x";
                } else {
                    cout << block;
                }
            }
            cout << endl;
        }
        */

        
        if (maze[h*2-2][w*2-2] != inf) {
            cout << maze[h*2-2][w*2-2] << endl;
        } else {
            cout << "0" << endl;
        }
    }
}