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++)
#define ALL(v) (v).begin(),(v).end()
#define int long long
typedef pair<int,int> P;

//-----------------------------------------------------------------------

int dy[]={-1,0,1,0};
int dx[]={0,-1,0,1};
const int INF=1e9;
int W,H;
int t[50][50][2];
int d[50][50];

bool isField(int y,int x){
    return (0<=y && y<H && 0<=x && x<W);
}
bool check(int y,int x,int dir){
    if(dir==0) return t[y-1][x][1];
    if(dir==1) return t[y][x-1][0];
    if(dir==2) return t[y][x][1];
    if(dir==3) return t[y][x][0];
}

int bfs(){
    REP(i,H) REP(j,W) d[i][j]=INF;
    d[0][0]=1;
    queue<P> que;
    que.push(P(0,0));

    while(!que.empty())
    {
	int y=que.front().first;
	int x=que.front().second;
	que.pop();
	if(y==H-1 && x==W-1) return d[H-1][W-1];
	REP(i,4){
	    int ny=y+dy[i], nx=x+dx[i];
	    if(isField(ny,nx) && !check(y,x,i) && d[ny][nx]==INF){
		d[ny][nx]=d[y][x]+1;
		que.push(P(ny,nx));
	    }
	}
    }
    return 0;
}

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    while(cin>>W>>H,W){
	REP(i,H-1){
	    REP(j,W-1) cin>>t[i][j][0];
	    REP(j,W) cin>>t[i][j][1];
	}
	REP(j,W-1) cin>>t[H-1][j][0];

	cout<<bfs()<<endl;
    }
}

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

constexpr int INF = 1 << 30;

struct Info {
    int h;
    int w;
    int dist;
};

int main()
{
    while (true) {
        int w, h;
        cin >> w >> h;
        if (w == 0 and h == 0) {
            break;
        }
        vector<vector<bool>> yoko(h, vector<bool>(w - 1, true));  // (h,w)->(h,w+1)
        vector<vector<bool>> tate(h - 1, vector<bool>(w, true));  // (h,w)->(h+1, w)
        for (int i = 0; i < 2 * h - 1; i++) {
            if (i % 2 == 0) {
                for (int j = 0; j < w - 1; j++) {
                    int c;
                    cin >> c;
                    yoko[i / 2][j] = (c == 0);
                }
            } else {
                for (int j = 0; j < w; j++) {
                    int c;
                    cin >> c;
                    tate[i / 2][j] = (c == 0);
                }
            }
        }
        vector<vector<bool>> visited(h, vector<bool>(w, false));
        queue<Info> q;
        q.push(Info{0, 0, 1});
        visited[0][0] = true;
        int distance = INF;
        while (not q.empty()) {
            const Info p = q.front();
            q.pop();
            if (p.h == h - 1 and p.w == w - 1) {
                distance = p.dist;
                break;
            }
            if (p.dist > h * w) {
                break;
            }
            if (p.h != h - 1 and tate[p.h][p.w] and (not visited[p.h + 1][p.w])) {
                visited[p.h + 1][p.w] = true;
                q.push(Info{p.h + 1, p.w, p.dist + 1});
            }
            if (p.h != 0 and tate[p.h - 1][p.w] and (not visited[p.h - 1][p.w])) {
                visited[p.h - 1][p.w] = true;
                q.push(Info{p.h - 1, p.w, p.dist + 1});
            }
            if (p.w != w - 1 and yoko[p.h][p.w] and (not visited[p.h][p.w + 1])) {
                visited[p.h][p.w + 1] = true;
                q.push(Info{p.h, p.w + 1, p.dist + 1});
            }
            if (p.w != 0 and yoko[p.h][p.w - 1] and (not visited[p.h][p.w - 1])) {
                visited[p.h][p.w - 1] = true;
                q.push(Info{p.h, p.w - 1, p.dist + 1});
            }
        }

        if (distance != INF) {
            cout << distance << endl;
        } else {
            cout << 0 << endl;
        }
    }
    return 0;
}