/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>
#include<bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n"
using namespace std;
using ll=long long;
using ld=long double;
ll mod = ll(1e9)+7;
ll inf = ll(1e18);
void bl(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

namespace dbg {
    using ll = long long;

    class Debug {
    public:
        Debug(){}
        template<typename T>
        void vd(vector<T> vec);
        template<typename T>
        void vd2(vector<vector<T>> vec);
        template<typename T>
        void ad(T *arr, ll n);
        template<typename T, size_t N>
        void ad2(T (&arr)[N], ll n);
        template<typename T>
        void md(T mp);
    };

    template<typename T>
    void Debug::vd(vector<T> vec) {
        for (auto vv : vec) cout << vv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::vd2(vector<vector<T>> vec) {
        for (auto vv : vec) {
            for (auto vvv : vv) cout << vvv << " ";
            cout << endl;
        }
    }

    template<typename T>
    void Debug::ad(T *arr, ll n) {
        for (int i = 0; i <= n; i++) cout << arr[i] << " ";
        cout << endl;
    }

    template<typename T, size_t N>
    void Debug::ad2(T (&arr)[N], ll n) {
        for (int i = 0; i <= N; i++) for (int j = 0; j <= n; j++) cout << arr[i][j] << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::md(T mp) {
        cout << "key : value" << endl;
        for (auto const &m : mp) cout << m.first << " : " << m.second << endl;
        cout << endl;
    }

}

#endif //INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

class a {
public:
    int w, h;
    vector<vector<ll>> dist;
    vector<vector<int>> wallx;
    vector<vector<int>> wally;

	void solve(std::istream& in, std::ostream& out) {
        while(true){
            int dummy;
            in >> w >> h;
            if(!w && !h) break;
            wallx.assign(h, vector<int>(w-1));
            wally.assign(h-1, vector<int>(w));
            for(int i=0; i<2*h-1; i++){
                if(i&1){
                    for(int j=0; j<w; j++){
                        in >> wally[i/2][j];
                    }
                }else{
                    for(int j=0; j<w-1; j++){
                        in >> wallx[i/2][j];
                    }
                }
            }

            dist.assign(h, vector<ll>(w, inf));
            queue<pair<int, int>> q;
            q.push(make_pair(0, 0));
            dist[0][0] = 1;
            while(!q.empty()){
                pair<int, int> u = q.front();
                q.pop();
                for(int i=0; i<4; i++){
                    int ny = u.first + dy[i];
                    int nx = u.second + dx[i];
                    if(nx < 0 || ny < 0 || nx >= w || ny >= h) continue;
                    if((dx[i] < 0 && wallx[ny][nx]) || (dx[i] > 0 && wallx[ny][nx-dx[i]])) continue;
                    if((dy[i] < 0 && wally[ny][nx]) || (dy[i] > 0 && wally[ny-dy[i]][nx])) continue;
                    if(dist[ny][nx] > dist[u.first][u.second] + 1) {
                        dist[ny][nx] = dist[u.first][u.second] + 1;
                        q.push(make_pair(ny, nx));
                    }
                }
            }
//
//            for(int i=0; i<h; i++){
//                for(int j=0; j<w; j++){
//                    cout << dist[i][j] << " ";
//                }
//                cout << enl;
//            }

            if(dist[h-1][w-1] == inf) out << 0 << enl;
            else out << dist[h-1][w-1] << enl;
        }
	}
};


int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
	a solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}



Measured memory_bytes: 3216