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 <iostream>
#include <queue>
using namespace std;

struct pos{
	int x;
	int y;
	int dis;
};

int main(){
	int w, h;
	while(cin >> w >> h, w != 0 && h != 0){
		int field[65][65];
		for(int i = 0; i < 65; i++){
            for(int j = 0; j < 65; j++){
                field[j][i] = 1;
            }
        }
		for(int i = 1; i <= h; i++){
			for(int j = 1; j <= w; j++){
				field[i*2-1][j*2-1] = 0;
			}
		}

		int l = 1;
		int input;
		for(int i = 1; i <= h*2-1; i++){
			if(i % 2 == 1){
				for(int j = 1; j <= w-1; j++){
					cin >> input;
					field[l*2-1][j*2] = input;
				}
			}else{
				for(int j = 1; j <= w; j++){
					cin >> input;
					field[l*2][j*2-1] = input;
				}
				l++;
			}
		}

		queue<pos> q;
		field[1][1] = 1;
		pos p;
		p.x = 1;
		p.y = 1;
		p.dis = 1;
		q.push(p);
		int x1[] = {-1, 0, 1, 0}, y1[] = {0, -1, 0, 1};
		while(!q.empty()){
			p = q.front();
			q.pop();
			for(int i = 0; i < 4; i++){
				pos p1 = p;
				p1.x += x1[i]; p1.y += y1[i];
				if(!field[p1.x][p1.y]){
					p1.dis++;
					field[p1.x][p1.y] = p1.dis;
					q.push(p1);
				}
 			}
		}

		int ans = (field[h*2-1][w*2-1] + 1) /2;

		for(int i = 0; i <= h*2; i++){
			for(int j = 0; j <= w*2; j++){
				cout << field[i][j] << " ";
			}
			cout << endl;
		}

		cout << ans << endl;

	}

	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

int main(){

    cin.tie(0);
    ios::sync_with_stdio(false);

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

    int w, h;
    vector<string> wall;
    vector< vector<int> > dist;
    int tx;
    int ty;

    while(cin >> w >> h, w){

        wall.resize((h << 1) - 1);

        cin.ignore();
        for (auto& x : wall)
            getline(cin, x);

        dist.assign(h, vector<int>(w, 0));
        dist[0][0] = 1;

        for(int d = 1; d < w * h; d++)
            for(int y = 0; y < h; y++)
                for(int x = 0; x < w; x++)
                    if(dist[y][x] == d)
                        for(int r = 0; r < 4; r++){
                            tx = x + dx[r];
                            ty = y + dy[r];

                            if(0 > tx || tx >= w || 0 > ty || ty >= h)
                                continue;

                            if(dist[ty][tx] != 0)
                                continue;

                            if (wall[ty + y][tx + x] == '0')
                                dist[ty][tx] = d + 1;
                        }

        cout << dist[h-1][w-1] << endl;

    }

    return 0;

}

C++: #include <bits/stdc++.h>
using namespace std;
using vi=vector<int>;
using vvi=vector<vi>;
using vs=vector<string>;
using msi=map<string,int>;
using mii=map<int,int>;
using pii=pair<int,int>;
using vlai=valarray<int>;
using ll=long long;
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define range(i,s,n) for(int i=s;i<n;i++)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define fs first
#define sc second
constexpr int gcd(int a,int b){return b?gcd(b,a%b):a;}
constexpr int lcm(int a,int b){return a*b/gcd(a,b);}

int main(){
    int w,h;
    while(cin>>w>>h,w){
        cin.ignore();
        vvi v(h*2+1,vi(w*2+1,1));
        rep(i,h*2-1){
            string s;
            getline(cin,s);
            replace(all(s),' ','0');
            if(i%2==0)s+="0";
            s="1"+s+"1";
            rep(j,w*2+1){
                v[i+1][j]=(s[j]=='1')?1:0;
            }
        }
        for(int i=1;i<v.size()-1;i+=2)
            for(int j=2;j<v[0].size()-1;j+=2)
                    if(v[i][j] && i<v.size()-3 && v[i+2][j]) v[i+1][j]=1;
        for(int i=2;i<v.size()-1;i+=2)
            for(int j=1;j<v[0].size()-1;j+=2)
                if(v[i][j] && j<v[0].size()-3 && v[i][j+2]) v[i][j+1]=1;
        //for(auto l:v){for(auto i:l)cout<<(i?"#":" ");cout<<endl;}
        v[1][1]=1;
        queue<pii> spot;
        spot.emplace(1,1);
        while(!spot.empty()){
            vi vec={1,0,-1,0,1};
            auto c=spot.front();
            spot.pop();
            rep(i,4){
                if(v[c.fs+vec[i]][c.sc+vec[i+1]]==0 && v[c.fs+vec[i]*2][c.sc+vec[i+1]*2]==0){
                    v[c.fs+vec[i]*2][c.sc+vec[i+1]*2] = v[c.fs][c.sc]+1;
                    spot.emplace(c.fs+vec[i]*2, c.sc+vec[i+1]*2);
                }
            }
        }
        //for(auto l:v){for(auto i:l)if(i==1)cout<<"###";else cout<<setw(3)<<i;cout<<endl;}
        cout<<v[h*2-1][w*2-1]<<endl;
    }
}