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 <algorithm>
#include <cstdio>
#include <functional>
#include <numeric>
#include <queue>
#include <vector>

using namespace std;

constexpr int INF = 99999999;
struct V {
    bool exist = false;
    int d = INF;
    int prev = 0;
    V() = default;
    V(bool e, int dd, int p)
        : exist{e}
        , d{dd}
        , prev{p}
    {
    }
};

int main()
{
    while (true) {
        size_t w;
        size_t h;
        scanf("%ld %ld", &w, &h);

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

        const auto size = w * h;

        vector<vector<V>> am{size};
        for (auto&& r : am) {
            r.resize(size);
        }

        vector<pair<int, int>> es;
        for (size_t i = 0; i < 2 * h - 1; ++i) {
            if (i % 2 == 0) {
                for (size_t j = 0; j < w - 1; ++j) {
                    int t;
                    scanf("%d", &t);
                    if (t == 0) {
                        auto id = j + (i / 2) * w;
                        es.push_back(make_pair(id, id + 1));
                        am[id][id + 1] = V(true, INF, 0);
                        am[id + 1][id] = V(true, INF, 0);
                    }
                }
            }
            else {
                for (size_t j = 0; j < w; ++j) {
                    int t;
                    scanf("%d", &t);
                    if (t == 0) {
                        auto id = j + (i / 2) * w;
                        es.push_back(make_pair(id, id + w));
                        am[id][id + w] = V(true, INF, 0);
                        am[id + w][id] = V(true, INF, 0);
                    }
                }
            }
        }

        am[0][0].d = 1;
        am[0][0].exist = true;
        using TT = pair<size_t, V>;
        vector<TT> q;
        for (size_t i = 0; i < am.size(); ++i) {
            for (size_t j = 0; j < am.size(); ++j) {
                if (am[i][j].exist) {
                    q.push_back(make_pair(i, am[i][j]));
                    break;
                }
            }
        }
        while (!q.empty()) {
            auto it =
                min_element(begin(q), end(q), [](const TT& l, const TT& r) {
                    return l.second.d < r.second.d;
                });
            auto u = *it;
            q.erase(it);
            for (size_t i = 0; i < am.size(); ++i) {
                auto&& v = am[u.first][i];
                if (v.exist) {
                    auto alt = u.second.d + 1;
                    if (v.d > alt) {
                        v.d = alt;
                        for (size_t j = 0; j < q.size(); ++j) {
                            if (q[j].first == i) {
                                q[j].second.d = alt;
                            }
                        }
                    }
                }
                am[i][u.first] = v;
            }
        }
        int min = 0;
        auto it = min_element(begin(am[size - 1]), end(am[size - 1]),
                              [](const V& l, const V& r) { return l.d < r.d; });
        if (it->d != INF) {
            min = it->d;
        }

        // for (size_t i = 0; i < am.size(); ++i) {
        //    auto&& v = am[size - 1][i];
        //    if (v.exist) {
        //        if (v.d < min) {
        //            min = v.d;
        //        }
        //    }
        //}
        // if (min == INF) {
        //    min = 0;
        //}
        printf("%d\n", min);
    }
}