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<vector>
#include<set>
#include<utility>
using namespace std;

unsigned int calc(const pair<int,int>& cur,set< pair<int,int> > pass,const int& w,const int& h,vector< vector<int> >& vwall,vector< vector<int> >& hwall){
	unsigned int sub,ret=-1;
	if(cur.first==w-1&&cur.second==h-1)return pass.size();
	if(pass.find(cur)!=pass.end())return -1;
	pass.insert(cur);
	if(cur.first!=0){
		if(vwall[cur.second][cur.first-1]!=1){
			sub=calc(pair<int,int>(cur.first-1,cur.second),pass,w,h,vwall,hwall);
			if(sub<ret)ret=sub;
		}
	}
	if(cur.first!=w-1){
		if(vwall[cur.second][cur.first]!=1){
			sub=calc(pair<int,int>(cur.first+1,cur.second),pass,w,h,vwall,hwall);
			if(sub<ret)ret=sub;
		}
	}
	if(cur.second!=0){
		if(hwall[cur.second-1][cur.first]!=1){
			sub=calc(pair<int,int>(cur.first,cur.second-1),pass,w,h,vwall,hwall);
			if(sub<ret)ret=sub;
		}
	}
	if(cur.second!=h-1){
		if(hwall[cur.second][cur.first]!=1){
			sub=calc(pair<int,int>(cur.first,cur.second+1),pass,w,h,vwall,hwall);
			if(sub<ret)ret=sub;
		}
	}
	return ret;
}
int main(){
	while(true){
		int w,h;
		unsigned int ret;
		vector< vector<int> > vwall,hwall;
		set< pair<int,int> > passed;
		cin>>w>>h;
		if(w==0)break;
		vwall.resize(h);
		hwall.resize(h-1);
		for(int y=0;y<h-1;y++){
			vwall[y].resize(w-1);
			hwall[y].resize(w);
			for(int x=0;x<w-1;x++){
				cin>>vwall[y][x];
			}
			for(int x=0;x<w;x++){
				cin>>hwall[y][x];
			}
		}
		vwall[h-1].resize(w-1);
		for(int x=0;x<w-1;x++){
			cin>>vwall[h-1][x];
		}
		ret=calc(pair<int,int>(0,0),passed,w,h,vwall,hwall);
		cout<<((ret==-1)?0:ret+1)<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int get_index(int x, int y, int w) {
	return x + y * w;
}

void add_edge(vector<vector<int>> &G, int x1, int y1, int x2, int y2, int w) {
	const int a = get_index(x1, y1, w);
	const int b = get_index(x2, y2, w);
	G[a].emplace_back(b);
	G[b].emplace_back(a);
}

int bfs(int s, int g, const vector<vector<int>> &G) {
	const int n = G.size();
	vector<int> dist(n, -1);
	dist[s] = 1;

	queue<int> que;
	que.push(s);

	while(!que.empty()) {
		const int v = que.front();
		que.pop();

		if(v == g) return dist[g];

		for(const auto &to : G[v]) {
			if(dist[to] == -1) {
				dist[to] = dist[v] + 1;
				que.push(to);
			}
		}
	}

	return -1;
}

int main() {
	for(int w, h; cin >> w >> h && w;) {
		const int n = w * h;
		vector<vector<int>> G(n);

		for(int i = 0; i < h; ++i) {
			// horizontal
			for(int j = 0; j < w - 1; ++j) {
				int ng;
				cin >> ng;

				if(!ng) add_edge(G, j, i, j + 1, i, w);
			}

			// vertical
			if(i != h - 1) {
				for(int j = 0; j < w; ++j) {
					int ng;
					cin >> ng;

					if(!ng) add_edge(G, j, i, j, i + 1, w);
				}
			}
		}

		const int ans = bfs(get_index(0, 0, w), get_index(w - 1, h - 1, w), G);
		cout << (ans == -1 ? 0 : ans) << endl;
	}

	return 0;
}