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<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};

int w, h;
struct sqdata {
    int left; int up; int right; int down;
};
struct xydata {
    int x; int y; int cnt;
};

int main() {
    while(1) {
        cin >> w >> h;
        if(w == 0 && h == 0) break;
        vector< vector<sqdata> > maze(h, vector<sqdata>(w));
        vector< vector<bool> > visitmaze(h, vector<bool>(w, false));
        for(int i = 0; i < 2*h-1; ++i) {
            int wall;
            if(i % 2 == 0) {
                int imaze = i/2;
                for(int j = 0; j < w-1; ++j) {
                    cin >> wall;
                    if(j == 0) {
                        maze.at(imaze).at(j).left = 1;
                    }
                    maze.at(imaze).at(j).right = wall;
                    maze.at(imaze).at(j+1).left = wall;
                    if(j+1 == w-1) {
                        maze.at(imaze).at(j+1).right = 1;
                    }
                }
            }else {
                int imaze = i/2;
                for(int j = 0; j < w; ++j) {
                    cin >> wall;
                    if(imaze == 0) {
                        maze.at(imaze).at(j).up = 1;
                    }
                    maze.at(imaze).at(j).down = wall;
                    maze.at(imaze+1).at(j).up = wall;
                    if(imaze+1 == h-1) {
                        maze.at(imaze+1).at(j).down = 1;
                    }
                }
            }
        }

        /*for(int i = 0; i < h; ++i) {
            for(int j = 0; j < w; ++j) {
                cout << "x y " << j << " " << i << ": ";
                cout << "left up right down ";
                cout << maze.at(i).at(j).left << " " << maze.at(i).at(j).up << " " << maze.at(i).at(j).right << " " << maze.at(i).at(j).down << endl;
            }
        }*/

        xydata first;
        first.x = 0; first.y = 0; first.cnt = 1;
        queue<xydata> que;
        que.push(first);

        int ans = 0;
        while(!que.empty()) {
            xydata now = que.front();
            que.pop();
            if(now.x == w-1 && now.y == h-1) {
                ans = now.cnt;
                break;
            }
            int nx, ny;
            int ncnt = now.cnt+1;
            if(maze.at(now.y).at(now.x).left == 0) {
                nx = now.x-1; ny = now.y;
                if(nx >= 0 && nx < w && ny >= 0 && ny < h) {
                    if(!visitmaze.at(ny).at(nx)) {
                        visitmaze.at(ny).at(nx) = true;
                        xydata next;
                        next.x = nx; next.y = ny; next.cnt = ncnt;
                        que.push(next);
                    }
                }
            }
            if(maze.at(now.y).at(now.x).up == 0) {
                nx = now.x; ny = now.y-1;
                if(nx >= 0 && nx < w && ny >= 0 && ny < h) {
                    if(!visitmaze.at(ny).at(nx)) {
                        visitmaze.at(ny).at(nx) = true;
                        xydata next;
                        next.x = nx; next.y = ny; next.cnt = ncnt;
                        que.push(next);
                    }
                }
            }
            if(maze.at(now.y).at(now.x).right == 0) {
                nx = now.x+1; ny = now.y;
                if(nx >= 0 && nx < w && ny >= 0 && ny < h) {
                    if(!visitmaze.at(ny).at(nx)) {
                        visitmaze.at(ny).at(nx) = true;
                        xydata next;
                        next.x = nx; next.y = ny; next.cnt = ncnt;
                        que.push(next);
                    }
                }
            }
            if(maze.at(now.y).at(now.x).down == 0) {
                nx = now.x; ny = now.y+1;
                if(nx >= 0 && nx < w && ny >= 0 && ny < h) {
                    if(!visitmaze.at(ny).at(nx)) {
                        visitmaze.at(ny).at(nx) = true;
                        xydata next;
                        next.x = nx; next.y = ny; next.cnt = ncnt;
                        que.push(next);
                    }
                }
            }
        }
        cout << ans << endl;
    }
}