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 <stdio.h>
#include <stdlib.h>
#include<math.h>
#include<vector>
#include<map>
#include<utility>
#include<algorithm>
using namespace std;

#define MAX 30
#define INF 1000
int wn,hn;
int d[MAX][MAX];
bool w[MAX][MAX]; //w,h ?¨??£?
bool h[MAX][MAX]; //????£?
vector< pair<int, int> > nextlist; //x,y
typedef std::pair<int, int> Pos;

void reset() {
	for (int i = 0; i < wn; i++) {
		for (int j = 0; j < hn; j++) {
			d[i][j] = INF;
		}
	}
}

bool sortRule(Pos left, Pos right) {
	return d[left.first][left.second] < d[right.first][right.second];
}


void maze(Pos pos) {
	nextlist.erase(nextlist.begin());
	//???
	if (pos.second > 0) {
		if (!w[pos.first][pos.second - 1] && d[pos.first][pos.second - 1] > d[pos.first][pos.second] + 1) {
			d[pos.first][pos.second - 1] = d[pos.first][pos.second] + 1;
			Pos tmp(pos.first, pos.second - 1);
			nextlist.push_back(tmp);
		}
	}

	//???
	if (pos.first > 0) {
		if (!h[pos.first - 1][pos.second] && d[pos.first - 1][pos.second] > d[pos.first][pos.second] + 1) {
			d[pos.first - 1][pos.second] = d[pos.first][pos.second] + 1;
			Pos tmp(pos.first - 1, pos.second);
			nextlist.push_back(tmp);
		}
	}

	//???
	if (pos.second < hn-1) {
		if (!w[pos.first][pos.second] && d[pos.first][pos.second + 1] > d[pos.first][pos.second] + 1) {
			d[pos.first][pos.second + 1] = d[pos.first][pos.second] + 1;
			Pos tmp(pos.first, pos.second + 1);
			nextlist.push_back(tmp);
		}
	}

	//???
	if (pos.first < wn -1) {
		if (!h[pos.first][pos.second] && d[pos.first + 1][pos.second] > d[pos.first][pos.second] + 1) {
			d[pos.first + 1][pos.second] = d[pos.first][pos.second] + 1;
			Pos tmp(pos.first + 1, pos.second);
			nextlist.push_back(tmp);
		}
	}

	if (nextlist.size() > 0) {
		sort(nextlist.begin(), nextlist.end(), sortRule);
		maze(nextlist[0]);

	}
}



int main() {
	cin >> wn >> hn;
	while (wn + hn) {
		reset();
		for (int i = 0; i < hn-1; i++) {
			for (int j = 0; j < wn-1; j++) {
				cin >> h[j][i];
			}
			for (int j = 0; j < wn; j++) {
				cin >> w[j][i];
			}
		}
		for (int j = 0; j < wn - 1; j++) {
			cin >> h[j][hn - 1];
		}

		d[0][0] = 1;
		Pos tmp(0, 0);
		nextlist.push_back(tmp);
		maze(nextlist[0]);

		if (d[wn - 1][hn - 1] == INF) {
			cout << 0 << endl;
		}
		else {
			cout << d[wn - 1][hn - 1] << endl;
		}

		cin >> wn >> hn;
	}
	return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <vector>
#include <queue>

using namespace std;

int main(){
    int w,h;
    vector<int> L[900];
    int dist[900];
    
    while(true){
        scanf("%d %d",&w,&h);
        
        if(w == 0) break;
        
        int V = w * h;
        
        for(int i = 0;i < V;++i)
            L[i].clear();
        
        for(int i = 0,x;i < 2*h - 1;++i){
            if(i & 1){
                for(int j = 0;j < w;++j){
                    scanf("%d",&x);
                    
                    if(!x){
                        L[(i / 2) * w + j].push_back((i / 2 + 1) * w + j);
                        L[(i / 2 + 1) * w + j].push_back((i / 2) * w + j);
                    }
                }
            }else{
                for(int j = 0;j < w - 1;++j){
                    scanf("%d",&x);
                    
                    if(!x){
                        L[(i / 2) * w + j].push_back((i / 2) * w + j + 1);
                        L[(i / 2) * w + j + 1].push_back((i / 2) * w + j);
                    }
                }
            }
        }
        
        queue<int> Q;
        
        memset(dist,-1,sizeof dist);
        
        Q.push(0);
        dist[0] = 0;
        
        while(!Q.empty()){
            int cur = Q.front();
            Q.pop();
            
            for(int i = L[cur].size() - 1,to;i >= 0;--i){
                to = L[cur][i];
                
                if(dist[to] == -1){
                    Q.push(to);
                    dist[to] = 1 + dist[cur];
                }
            }
        }
        
        printf("%d\n",dist[h * w - 1] + 1);
    }
    
    return 0;
}