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 <algorithm>
#include <queue>
#include <map>
using namespace std;

int dx[] = { 1,0,-1,0 };
int dy[] = { 0,1,0,-1 };

int main()
{
	while (true) {
		int w, h;
		cin >> w >> h;

		if (w == 0 && h == 0) {
			break;
		}

		vector<vector<int>> tatekabe(h, vector<int>(w - 1, 0));
		vector<vector<int>> yokokabe(h - 1, vector<int>(w, 0));
		vector<vector<int>> f(w, vector<int>(h, 0));

		for (int i = 0; i < 2 * h - 1; i++) {
			if (i % 2 == 0) {
				for (int j = 0; j < w - 1; j++) {
					cin >> tatekabe[i / 2][j];
				}
			}
			else {
				for (int j = 0; j < w; j++) {
					cin >> yokokabe[i / 2][j];
				}
			}
		}

		int ans = 1;
		queue<pair<int, int>> q;
		q.push({ 0,0 });
		f[0][0] = 1;

		while (true) {
			if (q.empty() == true) {
				cout << 0 << endl;
				break;
			}

			unsigned int cnt = q.size();
			while (cnt != 0) {

				pair<int, int> temp = q.front();
				q.pop();
				cnt--;

				if (temp.first == w - 1 && temp.second == h - 1) {
					cout << ans << endl;
					break;
				}

				for (int i = 0; i < 4; i++) {
					bool flag = true;
					int nx = temp.first + dx[i];
					int ny = temp.second + dy[i];

					if (nx < 0 || nx >= w || ny < 0 || ny >= h) {
						continue;
					}

					switch (i) {
					case 0:
						if (tatekabe[temp.second][temp.first] == 1) {
							flag = false;
						}
						break;
					case 1:
						if (yokokabe[temp.second][temp.first] == 1) {
							flag = false;
						}
						break;
					case 2:
						if (tatekabe[temp.second][temp.first - 1] == 1) {
							flag = false;
						}
						break;
					case 3:
						if (yokokabe[temp.second - 1][temp.first] == 1) {
							flag = false;
						}
						break;
					}

					if (flag == true && f[nx][ny] == 0) {
						q.push({ nx,ny });
						f[nx][ny] = 1;
					}
				}
			}
			ans++;
		}
	}

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

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

int main() {
	int w, h;
	while (cin >> w >> h, w) {
		int move[2] = { -w,w };
		vector<vector<int>>v(w*h,vector<int>(w*h));
		int a;
		for (int i = 0; i < h - 1; i++) {
			for (int j = 0; j < w - 1; j++) {
				cin >> a;
				v[w*i + j][w*i + j + 1] = a;
				v[w*i + j + 1][w*i + j] = a;
			}
			for (int j = 0; j < w; j++) {
				cin >> a;
				v[w*i + j][w*i + j + w] = a;
				v[w*i + j + w][w*i + j] = a;
			}
		}
		for (int i = 0; i < w-1; i++) {
			cin >> a;
			v[w*(h - 1) + i][w*(h - 1) + i + 1] = a;
			v[w*(h - 1) + i + 1][w*(h - 1) + i] = a;
		}
		queue<int> q;
		vector<int>mem(w*h);
		q.push(0); mem[0] = 1;
		while (!q.empty()) {
			int buf = q.front();
			if (buf == w*h - 1) {
				break;
			}
			if (buf%w != w - 1) {
				if (v[buf][buf + 1] == 0 && mem[buf + 1] == 0) {
					q.push(buf + 1); mem[buf + 1] = mem[buf]+1;
				}
			}
			if (buf%w != 0) {
				if (v[buf][buf - 1] == 0 && mem[buf - 1] == 0) {
					q.push(buf - 1); mem[buf - 1] = mem[buf]+1;
				}
			}
			for (int j = 0; j < 2; j++) {
				if (buf + move[j] >= 0 && buf + move[j] < w*h) {
					if (mem[buf + move[j]] == 0 && v[buf][buf + move[j]] == 0) {
						q.push(buf + move[j]); mem[buf + move[j]] = mem[buf] + 1;
					}
				}
			}
			q.pop();
		}
		cout << mem[w*h-1] << endl;
	}
}