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

#define DEBUG(x) // cerr << #x << " = " << x << endl

typedef pair<int, int> P;

int D[30][30][4];
int dist[30][30];

int main() {
    for(int W, H; cin >> W >> H, W + H > 0; ) {
        for(int x = 0; x < W - 1; x++) {
            int k; cin >> k;
            D[0][x][0] = D[0][x + 1][2] = k;
        }
        for(int y = 0; y < H - 1; y++) {
            for(int x = 0; x < W; x++) {
                int k; cin >> k;
                D[y][x][3] = D[y + 1][x][1] = k;
            }
            for(int x = 0; x < W - 1; x++) {
                int k; cin >> k;
                D[y + 1][x][0] = D[y + 1][x + 1][2] = k;
            }
        }

        P g = P(H - 1, W - 1);
        for(int i = 0; i < H; i++) {
            for(int j = 0; j < W; j++) {
                dist[i][j] = -1;
            }
        }
        queue<P> Q;
        Q.push(P(0, 0));
        dist[0][0] = 1;
        int ans = 0;
        while(!Q.empty()) {
            P p = Q.front(); Q.pop();
            DEBUG(p.first); DEBUG(p.second);
            if(p == g) {
                ans = dist[p.first][p.second];
                break;
            }
            const int dy[4] = { 0, -1, 0, 1 };
            const int dx[4] = { 1, 0, -1, 0 };
            for(int i = 0; i < 4; i++) {
                int ny = p.first + dy[i];
                int nx = p.second + dx[i];
                DEBUG(i);
                DEBUG(ny); DEBUG(nx);
                DEBUG(D[p.first][p.second][i]);
                if(!(0 <= nx && nx < W && 0 <= ny && ny < H)) continue;
                if(D[p.first][p.second][i] == 1 || dist[ny][nx] != -1) continue;
                DEBUG(ny); DEBUG(nx);
                Q.push(P(ny, nx));
                dist[ny][nx] = dist[p.first][p.second] + 1;
            }
        }
        cout << ans << endl;
    }
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <tuple>
#include <queue>
#include <stack>
#include <set>
#include <map>

using namespace std;

class Solver {
};

int main() {
	while (true) {
		int w, h;
		cin >> w >> h;
		if (w == 0)break;

		vector<vector<vector<bool>>> movable(
			h, vector<vector<bool>>(w, vector<bool>(4, false)));
		for (int i = 0; i < 2 * h - 1; i++) {
			if (i % 2 == 0) {
				for (int j = 0; j < w - 1; j++) {
					int v;
					cin >> v;
					if (v == 0) {
						movable[i / 2][j][0] = true;
						movable[i / 2][j + 1][2] = true;
					}
				}
			}
			else {
				for (int j = 0; j < w; j++) {
					int v;
					cin >> v;
					if (v == 0) {
						movable[i / 2][j][3] = true;
						movable[i / 2 + 1][j][1] = true;
					}
				}
			}
		}

		vector<vector<int>> distance(h, vector<int>(w, 1e9));
		queue<tuple<int,int,int>> que;
		que.emplace(make_tuple(0, 0, 1));
		while (!que.empty()) {
			auto val = que.front();
			int y = get<0>(val);
			int x = get<1>(val);
			int d = get<2>(val);
			que.pop();
			if (d >= distance[y][x])continue;
			distance[y][x] = d;

			if (movable[y][x][0])que.emplace(make_tuple(y, x + 1, d + 1));
			if (movable[y][x][1])que.emplace(make_tuple(y - 1, x, d + 1));
			if (movable[y][x][2])que.emplace(make_tuple(y, x - 1, d + 1));
			if (movable[y][x][3])que.emplace(make_tuple(y + 1, x, d + 1));
		}
		if (distance[h - 1][w - 1] == 1e9) cout << 0 << endl;
		else cout << distance[h - 1][w - 1] << endl;
	}
}