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;
template <typename T> using V = vector<T>;
template <typename T> using VV = V<V<T>>;

template <typename T>
T make_v(T init) { return init; }

template <typename T, typename... Tail>
auto make_v(T init, size_t s, Tail... tail) {
#define rec make_v(init, tail...)
    return V<decltype(rec)>(s, rec);
#undef rec
}

bool solve() {
    int H, W;
    cin >> W >> H;
    if(!(H + W)) return false;

    VV<int> wall(H * W);

    auto make_idx = [&](int h, int w) { return h * W + w; };
    auto check_range = [&](int h, int w) {
        return 0 <= h && h < H &&
               0 <= w && w < W;
    };

    for(int i = 0; i < H; i++) {
        for(int j = 0; j < W - 1; j++) {
            int a;
            cin >> a;
            if(a == 1) {
                wall[make_idx(i, j)].push_back(make_idx(i, j + 1));
                wall[make_idx(i, j + 1)].push_back(make_idx(i, j));
            }
        }
        if(i == H - 1) break;
        for(int j = 0; j < W; j++) {
            int a;
            cin >> a;
            if(a == 1) {
                wall[make_idx(i, j)].push_back(make_idx(i + 1, j));
                wall[make_idx(i + 1, j)].push_back(make_idx(i, j));
            }
        }
    }
    
    VV<int> edges(H * W);

    int dh[] = { 1, 0, -1, 0 };
    int dw[] = { 0, 1, 0, -1 };

    for(int h = 0; h < H; h++) for(int w = 0; w < W; w++) {
        for(int i = 0; i < 4; i++) {
            int nh = h + dh[i], nw = w + dw[i];
            if(!check_range(nh, nw)) continue;
            int hw_idx = make_idx(h, w);
            int nhw_idx = make_idx(nh, nw);
            auto ite = find(wall[hw_idx].begin(), wall[hw_idx].end(), nhw_idx);
            if(ite == wall[hw_idx].end()) edges[hw_idx].push_back(nhw_idx);
        }
    }

    const int inf = 1e9;
    V<int> dist(H * W, inf);
    dist[0] = 0;
    queue<pair<int, int>> que;
    que.emplace(0, 0);
    while(que.size()) {
        int idx, d;
        tie(idx, d) = que.front();
        que.pop();
        if(dist[idx] < d) continue;
        int nd = d + 1;
        for(int nidx : edges[idx]) {
            if(dist[nidx] <= nd) continue;
            dist[nidx] = nd;
            que.emplace(nidx, nd);
        }
    }

    int ans = dist.back();
    if(ans == inf) ans = -1;
    ans++;
    cout << ans << endl;
    return true;
}

int main() {
    while(solve());
    return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<set>
#include<stack>
#include<functional>
#include<list>
#include<unordered_map>
using namespace std;

vector<int>rinsetu[900];
int main() {;
	int a, b;
	while (cin >> b >> a, a | b) {
		for (int c = 0; c < a*2-1; c++) {
			cout << "#" << endl;
			if (c & 1) {
				for (int d = 0; d < b; d++) {
					int e; scanf("%d", &e);
					if (e == 0) {
						rinsetu[(c / 2)*b + d].push_back((c / 2 + 1)*b + d);
						rinsetu[(c / 2+1)*b + d].push_back((c / 2)*b + d);
					}
				}
			}
			else {
				char f; scanf("%c", &f);
				for (int d = 0; d < b - 1; d++) {
					int e; scanf("%d", &e);
					if (e)continue;
					rinsetu[(c / 2)*b + d].push_back((c / 2)*b + d + 1);
					rinsetu[(c / 2)*b + d+1].push_back((c / 2)*b + d);
				}
			}
		}
		int mincost[900]{};
		queue<int>Q;
		mincost[0] = 1;
		Q.push(0);
		while (Q.size()) {
			int t = Q.front(); Q.pop();
			for (int i : rinsetu[t]) {
				if (mincost[i] == 0) {
					mincost[i] = mincost[t] + 1;
					Q.push(i);
				}
			}
		}
		if (mincost[a*b - 1] == 0)puts("0");
		else cout << mincost[a*b - 1] << endl;
	}
}