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>
#define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep1(i, n) for (int i = 1; i < (n); ++i)
using namespace std;
typedef long long ll;
const int di[] = {0, 1, 0, -1};
const int dj[] = {1, 0, -1, 0};
const int dwi[] = {1, 2, 1, 0};
const int dwj[] = {1, 0, 0, 0};


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

    while(1){

        int w, h;
        cin >> w >> h;

        if(w == 0) break;

        vector<vector<int>> wall(2*h+1, vector<int>(w+1, 2));
        rep1(i, 2*h){
            if(i%2) rep1(j, w) cin >> wall[i][j];
            else rep(j, w) cin >> wall[i][j];
        }

        const int INF = 1001001001;
        vector<vector<int>> dist(h, vector<int>(w, INF));
        dist[0][0] = 0;
        queue<pair<int, int>> q;
        q.push((make_pair(0, 0)));

        while(!q.empty()){
            int i = q.front().first;
            int j = q.front().second;
            q.pop();

            rep(dir, 4){
                int ni = i + di[dir];
                int nj = j + dj[dir];
                int wi = 2*i + dwi[dir];
                int wj = j + dwj[dir];

                if(wi<0 || wi>=2*h+1 || wj<0 || wj>=w+1) continue;
                if(ni<0 || ni>=h || nj<0|| nj>=w) continue;
                if(wall[wi][wj] != 0) continue;
                if(dist[ni][nj] != INF) continue;

                dist[ni][nj] = dist[i][j] + 1;
                q.push(make_pair(ni, nj));
            }
        }

        if(dist[h-1][w-1] == INF) cout << 0 << endl;
        else cout << dist[h-1][w-1]+1 <<endl;
    }

    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <iomanip>

#include <vector>
#include <map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <utility>

#include <numeric>
#include <algorithm>
#include <functional>

#include <cctype>

#include <complex>
#include <string>
#include <sstream>

using namespace std;

#define all(c) c.begin(),c.end()
#define rall(c) c.rbegin(),c.rend()
#define rep(i,n) for(unsigned int i=0;i<(n);i++)
#define tr(it,container) for(typeof(container.begin()) it = container.begin(); \
                                                  it != container.end(); ++it)
#define mp(a,b) make_pair((a),(b))

typedef long long ll;
typedef complex<double> P;
const int dx[] = {1,0,-1,0};
const int dy[] = {0,-1,0,1};
const double EPS = 1e-9;
const int days[] = {31,28,31,30,31,30,31,31,30,31,30,31};
const int daysleap[] = {31,29,31,30,31,30,31,31,30,31,30,31};

int main(){
    while(true){
        int w,h;
        cin >> w >> h;
        if(w == 0) break;
        // ue sita hidari migi
        // -> migi ue hidari sita
        vector<vector<vector<char> > > Field(h,vector<vector<char> >(w,vector<char>(4,0)));

        rep(i,2*h-1){
            if(i % 2 == 0){
                rep(j,w-1){
                    int x;
                    cin >> x;
                    Field[i/2][j][0] = x==0;
                    Field[i/2][j+1][2] = x==0;
                }
            }else{
                rep(j,w){
                    int x;
                    cin >> x;
                    Field[i/2][j][3] = x==0;
                    Field[i/2+1][j][1] = x==0;
                }
            }
        }
        //y,x,depth
        queue<pair<pair<int,int>,int> > Q;
        Q.push(mp(mp(0,0),0));
        vector<vector<char> > ALR(h,vector<char>(w,0));
        ALR[0][0] = true;
        int gg = -1;
        while(!Q.empty()){
            pair<pair<int,int>,int> p = Q.front();
            ALR[p.first.first][p.first.second] = true;
            if(p.first.first == h-1 and p.first.second == w-1){
                gg = p.second;
                break;
            }
            Q.pop();
            rep(i,4){
                if(!Field[p.first.first][p.first.second][i]) continue;
                int ny = p.first.first + dy[i];
                int nx = p.first.second + dx[i];
                if(ALR[ny][nx]) continue;
                Q.push(mp(mp(ny,nx),p.second+1));
            }
        }
        if(gg == -1){
            cout << 0 << endl;
        }else{
            cout << gg+1 << endl;
        }
    }
    return 0;
}