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)<(int)(n);++(i))
using ll = long long;

int hw[100][100];
int hw2[50][50];

int main() {
    int w, h;
    while (cin >> w >> h and (w or h)) {

        rep(i, h*2-1) {
            if (i%2 == 0) {
                rep(j, w-1) {
                    int t;
                    cin >> t;
                    hw[i][ j * 2 + 1 ] = t;
                }
            }
            else {
                rep(j, w) {
                    int t;
                    cin >> t;
                    hw[i][ j * 2 ] = t;
                }
            }
        }

        using P = pair<int, int>;
        queue<P> que;
        que.push(P(0, 0));
        int dist[100][100];
        fill(dist[0], dist[100], 1e8);
        dist[0][0] = 1;

        int dx[] = { 1, 0, -1, 0 };
        int dy[] = { 0, 1, 0, -1 };
        while (que.size()) {
            P p = que.front(); que.pop();

            int x = p.second;
            int y = p.first;

            rep(d, 4) {
                int px = x + dx[d];
                int py = y + dy[d];
                if (0 <= px and px < w*2-1 and 0 <= py and py < h*2-1 and hw[py][px] == 0 and dist[py][px] == 1e8) {
                    dist[py][px] = dist[y][x] + 1;
                    dist[py+dy[d]][px+dx[d]] = dist[y][x] + 1;
                    que.push(P(py + dy[d], px + dx[d]));
                }
            }

        }

        cout << (dist[h*2-2][w*2-2] == 1e8 ? 0 : dist[h*2-2][w*2-2]) << endl;

        // rep(i, h*2-1) {
        //     rep(j, w*2-1) {
        //         cerr << dist[i][j] << " ";
        //     }
        //     cerr << endl;
        // }

    }
}

C++: #include<iostream>
#include<map>
#include<vector>
#include<algorithm>
#include<cmath>
#include<climits>
#include<ctime>
#include<cstring>
#include<numeric>
#include<queue>

#define REP(i,p,n) for(int i=p;i<(int)(n);++i)
#define rep(i,n) REP(i,0,n)

using namespace std;

int W, H;

int field[501][501];
const int INF=1<<28;

struct state {
	int x, y, d;
	state(int _x, int _y, int _d){
		x=_x;y=_y;d=_d;
	}
};

int dx[4] = {-1, 0, 1, 0};
int dy[4] = { 0,-1, 0, 1};

int solve() {
	int ans = INF;

	int gx = W-1, gy = H-1;

	queue<state> q;
	q.push(state(0, 0, 1));

	while (!q.empty()) {
		state s = q.front(); q.pop();

		if (s.d >= ans) continue;

		if (s.x == gx && s.y == gy) {
			ans = min(ans, s.d);
			continue;
		}

		for (int i=0; i<4; i++) {
			if (!(0 <= s.y + dy[i] && s.y + dy[i] < H && 0 <= s.x + dx[i] && s.x + dx[i] < W)) continue;

			if (field[s.y + dy[i]][s.x + dx[i]] == 0) {
				field[s.y + dy[i]][s.x + dx[i]] = -1;
				field[s.y + 2 * dy[i]][s.x + 2*dx[i]] = -1;
				q.push(state(s.x + 2*dx[i], s.y + 2*dy[i], s.d + 1));
			}
		}
	}

	if (ans == INF) ans = 0;
	return ans;
}

int main() {

	while (1) {
		cin >> W >> H;
		if (W == 0) break;
		W = 2*W - 1;
		H = 2*H - 1;

		fill_n((int *)field,sizeof(field)/sizeof(int),0);
		cin.ignore();

		string str;
		for (int i=0; i<H; i++) {
			getline(cin, str);

			int n = (int)str.size();
			for (int j=0; j<n; j++) {
				if (str[j] == '1') {
					field[i][j] = 1;
				}
			}
		}

		cout << solve() << endl;
	}

	return 0;
}