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()
using i64 = long long;
using P = pair<int,int>;


int main(){
    int W,H;
    while(cin >> W >> H, W != 0){
        W = 2*W - 1;
        H = 2*H - 1;
        vector<vector<bool>> maze(H, vector<bool>(W,0));
        for(int h = 1; h < H; h += 2){
            for(int w = 0; w < W; w++){
                maze[h][w] = true;
            }
        }
        for(int w = 1; w < W; w += 2){
            for(int h = 0; h < H; h++){
                maze[h][w] = true;
            }
        }

        for(int h = 0;h < H; h++){
            for(int w = (h%2 == 0); w < W; w += 2){
                bool c; 
                cin >> c;
                maze[h][w] = c;
            }
        }

        vector<vector<int>> dist(H,vector<int>(W,-1));
        dist[0][0] = 0;
        queue<P> que;
        que.push({0,0});
        
        const int d[4] = {1, -1, 0, 0};
        while(!que.empty()){
            P p = que.front();
            que.pop();
            int h = p.first;
            int w = p.second;
            for(int i = 0; i < 4; i++){
                int nh = h + d[i];
                int nw = w + d[i^2];

                if(nh < 0 || nh >= H || nw < 0 || nw >= W) continue;
                if(dist[nh][nw] != -1) continue;
                if(maze[nh][nw] == 1) continue;

                dist[nh][nw] = dist[h][w] + 1;
                que.push({nh, nw});
            }
        }

        int ans = dist[H-1][W-1] / 2 + 1;
        if(dist[H-1][W-1] == -1) ans = 0;
        cout << ans << endl;
    }
}

C++: #include <bits/stdc++.h>

using namespace std;

#define FOR(i,s,e) for(int (i)=(s);(i)<(int)(e);(i)++)
#define REP(i,e) FOR(i,0,e)

#define all(o) (o).begin(), (o).end()
#define psb(x) push_back(x)
#define UNIQUE(o) (o).erase(unique(sort(all((o)))))

typedef long long ll;
typedef pair<int, int> PII;

const int H = 30;
const int W = 30;
int h, w;
int ph[H][W], pv[H][W], usd[H][W];

int main() {
  while(scanf("%d%d ", &w, &h), w) {
    REP(i,h*2-1) {
      if (i&1) {
        REP(j,w) scanf("%d ", &(pv[i/2][j]));
      } else {
        REP(j,w-1) scanf("%d ", &(ph[i/2][j]));
      }
    }
    memset(usd, 0, sizeof(usd));
    queue<PII> q;
    q.push(make_pair(0, 0));
    usd[0][0] = 1;
    while (q.size()) {
      int i = q.front().first;
      int j = q.front().second;
      q.pop();

      if (j+1<w && !ph[i][j] && !usd[i][j+1]) {
        usd[i][j+1] = usd[i][j] + 1;
        q.push(make_pair(i,j+1));
      }
      if (j-1>=0 && !ph[i][j-1] && !usd[i][j-1]) {
        usd[i][j-1] = usd[i][j] + 1;
        q.push(make_pair(i,j-1));
      }
      if (i+1<h && !pv[i][j] && !usd[i+1][j]) {
        usd[i+1][j] = usd[i][j] + 1;
        q.push(make_pair(i+1,j));
      }
      if (i-1>=0 && !pv[i-1][j] && !usd[i-1][j]) {
        usd[i-1][j] = usd[i][j] + 1;
        q.push(make_pair(i-1,j));
      }
    }
    printf("%d\n", usd[h-1][w-1]);
  }
  return 0;
}