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>
using namespace std;

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

int iswall[32][32];
const int MAX_H = 30;
const int MAX_W = 30;
const int INF = 1e9;

int solve(int w, int h) {
	int memo[MAX_H][MAX_W];
	const static int dy[] = {1, 0, -1, 0};
	const static int dx[] = {0, 1, 0, -1};
	for (int i = 0; i < MAX_H; ++i) for (int j = 0; j < MAX_W; ++j) memo[i][j] = INF;

	queue<pair<int, int> > que;
	memo[0][0] = 1;
	que.push(make_pair(0, 0));
	while(!que.empty()) {
		pair<int, int> tmp = que.front(); que.pop();
		int y = tmp.first, x = tmp.second;
		// printf("y %d x %d\n", y, x);
		for (int i = 0; i < 4; ++i) {
			int ny = y + dy[i], nx = x + dx[i];
			if(!(0 <= ny && ny < h && 0 <= nx && nx < w)) continue; // ?????????
			if(memo[ny][nx] != INF) continue; // ?????§?????°???????????????
			// printf("ny %d nx %d\n", ny, nx);
			if(i % 2 == 0) { //????§????
				if(iswall[2 * y + 1][x]) continue;
			} else { //?¨??§????
				if(iswall[2 * y][min(x, nx)]) continue;
			}
			que.push(make_pair(ny, nx));
			memo[ny][nx] = memo[y][x] + 1;
		}
	}
	return memo[h - 1][w - 1] == INF ? 0 : memo[h - 1][w - 1];
}

int main(void) {
	while(1) {
		int w, h; scanf("%d %d", &w, &h);
		if(w == 0 && h == 0) break;
		for (int i = 0; i < 2 * h - 1; ++i) {
			for (int j = 0; j < w - (i % 2 ? 0 : 1); ++j) {
				scanf("%d", &iswall[i][j]);
			}
		}

		printf("%d\n", solve(w, h));
	}
	return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<cstdio>
#include<sstream>
#include<iomanip>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef pair<int,pii> pip;
typedef vector<pip>vip	;
const double PI=acos(-1);
const double EPS=1e-8;
const int inf=1e8;
int INF=100000;
int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};
vvi G;
void f(int x,int y){
	rep(i,4){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(G[nx][ny]==inf)continue;
		if(G[nx][ny]>G[x][y]+1){
			G[nx][ny]=G[x][y]+1;
			f(nx,ny);
		}
	}
}
int main(){
	int n,m;
	while(cin>>m>>n,n+m){
		G=vvi(2*n+1,vi(2*m+1,inf));
		rep(i,n)rep(j,m)G[i*2+1][j*2+1]=INF;
		G[1][1]=0;
		rep(i,n){
			rep(j,m-1){
				int a;
				cin>>a;
				if(!a)G[2*i+1][2*j+2]=INF;
			}
			if(i!=n-1){
				rep(j,m){
					int a;cin>>a;
					if(!a)G[2*i+2][2*j+1]=INF;
				}
			}
		}
		f(1,1);
//		rep(i,2*n+1){rep(j,2*m+1)cout<<" "<<G[i][j];cout<<endl;}
		if(G[2*n-1][2*m-1]==INF)cout<<0<<endl;
		else cout<<G[2*n-1][2*m-1]/2+1<<endl;
	}
}