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 lp(i,n) for(int i=0;i<n;i++)
int dp[50][50];
int a[50][50],b[50][50];

int dd(int w,int h){
	queue<tuple<int,int,int>> lis;
	lis.push(make_tuple(0,0,0));
	while(1){
		if(lis.empty()) break;
		tuple<int,int,int> memo=lis.front();
		lis.pop();
		int x,y,now;
		x=get<0>(memo);
		y=get<1>(memo);
		now=get<2>(memo);
		if(dp[x][y]<=now) continue;
		dp[x][y]=now;
		now++;
		if(a[x][y]==0&&x!=w-1) lis.push(make_tuple(x+1,y,now));
		if(b[x][y]==0&&y!=h-1) lis.push(make_tuple(x,y+1,now));
		if(x!=0){
			if(a[x-1][y]==0) lis.push(make_tuple(x-1,y,now));
		}
		if(y!=0){
			if(b[x][y-1]==0) lis.push(make_tuple(x,y-1,now));
		}
	}
	if(dp[w-1][h-1]==10000)
	return 0;
	else return dp[w-1][h-1]+1;
}

int main(){
	while(1){
		int w,h;
		cin>>w>>h;
		if(w==0&&h==0) break;
		lp(i,50){
			lp(j,50){
				a[i][j]=0;
				b[i][j]=0;
				dp[i][j]=10000;
			}
		}
		lp(i,h){
			lp(j,w-1){
				cin>>a[j][i];
			}
			if(i==h-1) break;
			lp(j,w){
				cin>>b[j][i];
			}
		}
		cout<<dd(w,h)<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
using namespace std;

typedef pair<int, int> P;
typedef pair<int, P> P2;
int W, H;

int T[30][30];
int V[30][30];

int DX[4] = {0, -1, 1, 0};
int DY[4] = {-1, 0, 0, 1};

int main() {
  while (cin >> W >> H) {
    if (W == 0 && H == 0) break;
    for (int i=0; i<H; i++) {
      for (int j=0; j<W; j++) {
        T[j][i] = 0;
        V[j][i] = 0;
      }
    }
    for (int i=0; i<H; i++) {
      for (int j=0; j<W-1; j++) {
        int x; cin >> x;
        if (x == 1) {
          T[j][i] |= 2;
          T[j+1][i] |= 4;
        }
      }
      if (i == H-1) continue;
      for (int j=0; j<W; j++) {
        int x; cin >> x;
        if (x == 1) {
          T[j][i]   |= 8;
          T[j][i+1] |= 1;
        }
      }
    }
    queue<P2> q;
    q.push(P2(1, P(0, 0)));
    V[0][0] = 1;
    while (!q.empty()) {
      int r = q.front().first,
          x = q.front().second.first,
          y = q.front().second.second; q.pop();

      for (int k=0; k<4; k++) {
        int dx = x + DX[k], dy = y + DY[k];
        if (dx < 0 || dx >= W || dy < 0 || dy >= H) continue;
        if (T[x][y] & (1<<k)) continue;
        if (V[dx][dy] != 0) continue;
        V[dx][dy] = r+1;
        q.push(P2(r + 1, P(dx, dy)));
      }
    }
    cout << V[W-1][H-1] << "\n";
  }
  return 0;
}

C++: #include<stdio.h>
#include<iostream>
#include<math.h>
#include<algorithm>
#include<string>
#define pi 3.14159
#define Inf 9999
using namespace std;



int w, h, a[59][59];
void dfs(int y, int x, int step);
int main(){
	while(1) {
		cin >> w >> h;
		if(w == 0 && h == 0) break;
		for(int i = 0; i < 2*h-1; i++) {
			for(int j = 0; j < 2*w-1; j++) {
				if(i % 2 == 0 && j % 2 == 0) a[i][j] = Inf;
				else if(i % 2 == 1 && j % 2 == 1) a[i][j] = Inf;
				else cin >> a[i][j];
			}
		}
		a[0][0] = 1;
		if(a[1][0] == 0) dfs(2, 0, 1);
		if(a[0][1] == 0) dfs(0, 2, 1);
		if(a[2*h-2][2*w-2] == Inf) cout << 0 <<endl;
		else cout << a[2*h-2][2*w-2] <<endl;
	}
	return 0;
}

void dfs(int y, int x, int step) {
	if(y < 0 || x < 0 || y >= 2*h-1 || x >= 2*w-1) return;
	if(step >= a[y][x]) return;
	else {
		step++;
		a[y][x] = step;
		if(y+1 < 2*h-1) { 
			if(a[y+1][x] == 0) dfs(y+2, x, step);
		}
		if(x + 1 < 2*w-1) {
			if(a[y][x+1] == 0) dfs(y, x+2, step);
		}
		if(y - 1 >= 0) {
			if(a[y-1][x] == 0) dfs(y-2, x, step);
		}
		if(x - 1 >= 0) {
			if(a[y][x-1] == 0) dfs(y, x-2, step);
		}
	}
	return;
}