#include <bits/stdc++.h>
using ll = long long;
using namespace std;
#define rep(i,n) for(int i=0, i##_len=(int)(n); i<i##_len; i++)
#define reps(i,n) for(int i=1 , i##_len=(int)(n);i<=i##_len;i++)
#define rrep(i,n) for(int i=((int)(n)-1);i>=0;i--)
#define rreps(i,n) for(int i=((int)(n));i>0;i--)
#define repi(i,x) for(auto i=(x).begin(),i##_fin=(x).end();i!=i##_fin;i++)
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define solve(a) ((a)?"Yes":"No")
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef pair<int , int> Pi;
typedef vector<Pi> VPi;
typedef vector<long long> V;
typedef vector<V> VV;
typedef pair<long long , long long> P;
typedef vector<P> VP;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1;} return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1;} return 0;}
const long long INFLL = 1LL<<50;
const int INF = 1<<30;
const double PI=acos(-1);
//ワーシャルフロイゼ法(隣接行列を受け取り、それぞれの最短を受け取る、size:10^2-)
//ダイクストラ法:スタートから任意の地点での最短距離を求める
//計算量:(頂点+辺)log(頂点) 
//始点,終点,隣接リスト(pathlist[edge.A]=(edgeB,legth))-->距離(notfound:INFLL);
vector<long long> Dikstra(int start,vector<vector<pair<int,long long>>>&pathlist){
	int edge=pathlist.size();
	pair<long long, int> cerching;
	priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> q; //start to distance,[ditance ,islandNo.]
	vector<long long> D(edge,INFLL); //distance (ans)
	vector<bool>had(edge,false);
	D[start] = 0;
	q.emplace(0LL, start);

	while (!q.empty()){
		cerching = q.top();
		q.pop();
		if (had[cerching.second] == false){
			had[cerching.second] = true;


			for (auto i = pathlist[cerching.second].begin(); i != pathlist[cerching.second].end(); i++){
				if (had[i->first] == false){
					chmin(D[i->first], (cerching.first) + (i->second));
					q.emplace(D[i->first], i->first);
				}
			}
		}
	}


return D;
}
//https://onlinejudge.u-aizu.ac.jp/challenges/search/volumes/1166
int main(){
	int w,h;
	ll ans=INFLL;
	int bef;
	pair<int,int>po=mp(0,0);
	vector<vector<pair<int, long long>>> path;
	while (1)
	{
		cin >> w >> h;
		if (h == w and h == 0)
		{
			return 0;
		}
		path.clear();
		path.resize(h*w);
		for (int i = 0; i < (2 * h) -1; i++)
		{
			for (int j = 0; j < w+((i % 2==0) ? -1 : 0); j++){
				cin >> bef;
				//
				/*
				if (i % 2 == 0)
				{
					clog << (i / 2) * w + (j) << " to " << (i / 2) * w +( j + 1) << " -- " << bef << endl;
				}
				else
				{
					clog << (i / 2) * w + (j) << " to " << ((i + 1) / 2) * w + (j)  << " -- " << bef << endl;
				}
				*/
				//
				if(!bef){
					if(i%2==0){
						path[(i / 2) * w + (j)].emplace_back((i / 2) * w + (j + 1), 1LL);
						path[(i / 2) * w + (j + 1)].emplace_back((i / 2) * w + (j), 1LL);
					}else{
						path[(i / 2) * w + (j)].emplace_back(((i + 1) / 2) * w + (j), 1LL);
						path[((i + 1) / 2) * w + (j)].emplace_back((i / 2) * w + (j), 1LL);
					}
					
				}
			}
		}
		//
		/*
		rep(i,h*w){
			repi(itr,path[i]){
				clog<<(itr->F)<<" ";
			}
			clog<<endl;
		}
		*/
		//
		ans=Dikstra(0,path)[h*w-1];
		if(ans==INFLL){
			cout<<0<<endl;
		}else{
		cout << ans+1 << endl;
	}
	}
}


Measured memory_bytes: 3160