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;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef complex<double> P;
typedef pair<int,int> pii;
#define REP(i,n) for(ll i=0;i<n;++i)
#define REPR(i,n) for(ll i=1;i<n;++i)
#define FOR(i,a,b) for(ll i=a;i<b;++i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define MOD (ll)(1e9+7)
#define ADD(a,b) a=((a)+(b))%MOD
#define FIX(a) ((a)%MOD+MOD)%MOD

#define INF (int)(1e9)

struct edge{int from,to,w;};
bool operator < (const edge &e, const edge &f) {
  return e.w != f.w ? e.w > f.w :
    e.from != f.from ? e.from < f.from : e.to < f.to;
}

vector<edge> g[100];


int w,h;
int getpos(int x,int y){
  return x*h+y;
}
int MAX_POS(){
  return w*h;
}

// http://www.prefield.com/algorithm/graph/dijkstra.html
vi dijkstra(int s) {
  vi dist(MAX_POS(),INF);
  dist[s] = 0;
  priority_queue<edge> Q; // "e < f" <=> "e.weight > f.weight"
  for (Q.push((edge){-2, s, 0}); !Q.empty(); ) {
    edge e = Q.top(); Q.pop();
    // if (prev[e.to] != -1) continue;
    REP(i,g[e.to].size()){
      edge f = g[e.to][i];
      if (dist[f.to] > e.w+f.w) {
        dist[f.to] = e.w+f.w;
        Q.push((edge){f.from, f.to, e.w+f.w});
      }
    }
  }
  return dist;
}

void addE(int from,int to){
  if(from>100 || to>100)return;
  g[from].push_back((edge){from,to,1});
  g[to].push_back((edge){to,from,1});
}

int main(){
  while(true){
    cin>>w>>h;
    if(w==0 && h==0)break;
    // init
    REP(i,100)g[i] = vector<edge>();
    // input
    REP(i,2*h-1){
      if(i%2==0){
        // yoko kabe
        REP(j,w-1){
          int t;
          cin >> t;
          if(t==0) addE(getpos(j,i/2),getpos(j+1,i/2));
          assert(j+1<=w-1);
          assert(i/2<=h-1);
        }
      }else{
        // tate kabe
        REP(j,w){
          int t;
          cin >> t;
          if(t==0) addE(getpos(j,i/2),getpos(j,i/2+1));
          assert(j<=w-1);
          assert(i/2+1<=h-1);
        }
      }
    }
    // dijkstra
    vi dist = dijkstra(0);
    if(dist[dist.size()-1]==INF){
      cout << 0 << endl;
    }else{
      cout << dist[dist.size()-1]+1 << endl;
    }
  }
  return 0;
}

C++: #include<stdio.h>
#include<algorithm>
#include<queue>
using namespace std;
int bfs[30][30];
int dat[100][100];
int main(){
	int a,b;
	while(scanf("%d%d",&a,&b),a){
		for(int i=0;i<2*b-1;i++){
			for(int j=0;j<a+i%2-1;j++){
				scanf("%d",&dat[i][j]);
			}
		}
		for(int i=0;i<30;i++)
			for(int j=0;j<30;j++)
				bfs[i][j]=0;
		bfs[0][0]=1;
		queue<pair<int,int> >Q;
		Q.push(make_pair(0,0));
		while(Q.size()){
			int row=Q.front().first;
			int col=Q.front().second;
			Q.pop();
			if(row){
				if(!dat[row*2-1][col]&&!bfs[row-1][col]){
					bfs[row-1][col]=bfs[row][col]+1;
					Q.push(make_pair(row-1,col));
				}
			}
			if(row<b-1){
				if(!dat[row*2+1][col]&&!bfs[row+1][col]){
					bfs[row+1][col]=bfs[row][col]+1;
					Q.push(make_pair(row+1,col));
				}
			}
			if(col){
				if(!dat[row*2][col-1]&&!bfs[row][col-1]){
					bfs[row][col-1]=bfs[row][col]+1;
					Q.push(make_pair(row,col-1));
				}
			}
			if(col<a-1){
				if(!dat[row*2][col]&&!bfs[row][col+1]){
					bfs[row][col+1]=bfs[row][col]+1;
					Q.push(make_pair(row,col+1));
				}
			}
		}
		printf("%d\n",bfs[b-1][a-1]);
	}
}