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++: /*
　　こんにちは。あたしはｶｳｶﾞｰﾙ。
　　redcoderになるためAtCoderを巡る旅をしてます。

　　　 　 ＿_
　　　 ヽ|＿_|ノ　　　　ﾓｫ
　　　　||‘‐‘||ﾚ　　_)_, ―‐ 、
　　　　/(Ｙ (ヽ＿ /・ ヽ　　 ￣ヽ
　　　　∠ ＿ ゝ　 ｀^ヽ ﾉ.::::_(ノヽ
　　　　 _/ヽ　 　　  /ヽ￣￣/ヽ
*/

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define dump(x) cout << #x << " = " << (x) << endl
#define YES(n) cout << ((n) ? "YES" : "NO") << endl
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl
#define POSSIBLE(n) cout << ((n) ? "POSSIBLE" : "IMPOSSIBLE") << endl
#define Possible(n) cout << ((n) ? "Possible" : "Impossible") << endl

#define rep(i, n) REP(i, 0, n)                  // 0, 1, ..., n-1
#define REP(i, x, n) for(int i = x; i < n; i++) // x, x + 1, ..., n-1
#define FOREACH(x, a) for(auto &(x) : (a))

#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()

#define COUT(x) cout << (x) << endl

template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}

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

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    vector<vector<int>> dist;
    vector<string> wall;

    int w, h;
    while(1) {
        cin >> w >> h;cin.ignore();
        if(w == 0 && h == 0) break;

        dist.assign(h, vector<int>(w, 0));
        wall.resize(h * 2 - 1);

        rep(i, h * 2 - 1) { getline(cin, wall[i]); }

        queue<pair<int, int>> que;
        dist[0][0] = 1;
        que.push({0, 0});

        while(!que.empty()) {
            pair<int, int> next = que.front();
            que.pop();
            int y = next.first, x = next.second;
            if(y == h - 1 && x == w - 1) break;
            rep(i, 4) {
                int ny = y + dy[i], nx = x + dx[i];
                if(ny < 0 || ny >= h || nx < 0 || nx >= w) continue;
                if(dist[ny][nx] != 0) continue;
                if(wall[y + ny][x + nx] != '0') continue;
                dist[ny][nx] = dist[y][x] + 1;
                que.push({ny, nx});
            }
        }
        COUT(dist[h - 1][w - 1]);
    }
}

C++: #include<stdio.h>
#include<iostream>
#include<math.h>
#include<algorithm>
#include<string>
#define pi 3.14159
#define Inf 99999
using namespace std;



int w, h, step, a[59][59];
void dfs(int y, int x);
int main(){
	while(1) {
		step = 1;
		cin >> w >> h;
		if(w == 0 && h == 0) break;
		for(int i = 0; i < 2*h-1; i++) {
			for(int j = 0; j < 2*w-1; j++) {
				if(i % 2 == 0 && j % 2 == 0) a[i][j] = Inf;
				else if(i % 2 == 1 && j % 2 == 1) a[i][j] = Inf;
				else cin >> a[i][j];
			}
		}
		a[0][0] = 1;
		if(a[1][0] == 0) dfs(2, 0);
		if(a[0][1] == 0) dfs(0, 2);
		if(a[2*h-2][2*w-2] == Inf) cout << 0 <<endl;
		else cout << a[2*h-2][2*w-2] <<endl;
		
	}
	return 0;
}

void dfs(int y, int x) {
	if(y < 0 || x < 0 || y >= 2*h-1 || x >= 2*w-1) return;
	if(step >= a[y][x]) return;
	else {
		step++;
		a[y][x] = step;
		if(y+1 < 2*h-1) { 
			if(a[y+1][x] == 0) dfs(y+2, x);
		}
		if(x + 1 < 2*w-1) {
			if(a[y][x+1] == 0) dfs(y, x+2);
		}
		if(y - 1 >= 0) {
			if(a[y-1][x] == 0) dfs(y-2, x);
		}
		if(x - 1 >= 0) {
			if(a[y][x-1] == 0) dfs(y, x-2);
		}
	}
	return;
}

C++: 
#include <algorithm>
#include <numeric>
#include <map>
#include <vector>
#include <iostream>
#include <queue>

using namespace std;

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


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

int INF=1<<28;
int main() {
	while (true) {
		int W,H;cin >> W >> H;if(W==0 && H==0)break;

		vector<vector<vector<bool>>> wall(H,vector<vector<bool>>(W,vector<bool>(4)));

		REP(inpy,2*H-1){
			int y=inpy/2;
			if(inpy%2==0){
				REP(x,W-1){
					int b;cin >> b;
					wall[y][x][0]=b;
					if(x-1>=0)wall[y][x-1][2]=b;
				}
			}else{
				REP(x,W){
					int b;cin >>b;
					wall[y][x][1]=b;
					if(x+1<W)wall[y][x+1][3]=b;
				}
			}
		}

		priority_queue<pair<int,pair<int,int>>,vector<pair<int,pair<int,int>>>,greater<pair<int,pair<int,int>>>> que;
		que.push(make_pair(0,make_pair(0,0)));
		vector<vector<int>> ds(H,vector<int>(W,INF));ds[0][0]=0;

		while(!que.empty()){
			pair<int,pair<int,int>> p=que.top();que.pop();
			int y=p.second.first,x=p.second.second;
			REP(d,4)if(!wall[y][x][d]){	
				
				int ny=y+dy[d],nx=x+dx[d];			
				if(0<=nx && nx < W && 0 <= ny && ny < H){
					if(ds[ny][nx]>ds[y][x]+1){
						que.push(make_pair(p.first+1,make_pair(ny,nx)));
						ds[ny][nx]=ds[y][x]+1;
					}
				}
			}
		}
		if(ds[H-1][W-1]!=INF)cout << ds[H-1][W-1]+1<<endl;
		else cout << 0 <<endl;
	}
}