#include <bits/stdc++.h>
//#define int long long

using namespace std;
using LL = long long;
using P = pair<int, int>;
using Tapris = tuple<int, int, int>;

#define REP(i, n) for(LL i = 0; i < n; ++i)
#define FOR(i, a, n) for(LL i = a; i < n; ++i)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()

const int INF = (int)1e9;
const LL INFL = (LL)1e15;
const int MOD = 1e9 + 7;

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

/*************** using variables ***************/
int w, h;
int dp[905][905];
/**********************************************/
struct Edge {
    int cost, to;
    Edge(int t, int c) {
        cost = c;
        to = t;
    }
    bool operator<(const Edge &e) const { return cost < e.cost; }
    bool operator>(const Edge &e) const { return cost > e.cost; }
};

template <typename T>
class Dijkstra {
    private:
        bool isDir = false;  // 無向グラフ: false, 有向グラフ: true
        T INF = numeric_limits<T>::max();
        int V;                     // 頂点数
        vector<vector<Edge>> adj;  // adj[始点][動的配列で始点から伸びる枝]
        vector<int> prever;

    public:
        Dijkstra(int n, bool dir);
        vector<T> cost;
        void AddEdge(int f, int t, int c);
        bool HasPath(int t);                 // tに至るパスはあるか
        vector<int> getShortestPath(int t);  // tへの最短路
        void Run(int f);
};

    template <typename T>
Dijkstra<T>::Dijkstra(int n, bool dir)
    : isDir(dir),
    V(n + 1),
    adj(vector<vector<Edge>>(V)),
    prever(vector<int>(V, -1)),
    cost(vector<T>(V)) {
        fill(cost.begin(), cost.end(), INF);
    }

template <typename T>
void Dijkstra<T>::AddEdge(int f, int t, int c) {
    adj[f].push_back(Edge(t, c));
    if (!isDir) adj[t].push_back(Edge(f, c));
}

template <typename T>
bool Dijkstra<T>::HasPath(int t) {
    return cost[t] != INF;
}

template <typename T>
vector<int> Dijkstra<T>::getShortestPath(int t) {
    vector<int> path;
    for (; t != -1; t = prever[t]) path.push_back(t);

    reverse(path.begin(), path.end());
    return path;
}

template <typename T>
void Dijkstra<T>::Run(int firstNode) {
    priority_queue<Edge, vector<Edge>, greater<Edge>> pq;

    cost[firstNode] = 0;
    pq.push(Edge(firstNode, 0LL));

    while (!pq.empty()) {
        Edge currentEdge = pq.top();
        pq.pop();

        if (cost[currentEdge.to] < currentEdge.cost) continue;

        for (Edge tmp : adj[currentEdge.to]) {
            T sumCost = currentEdge.cost + tmp.cost;
            if (cost[tmp.to] > sumCost) {
                cost[tmp.to] = sumCost;
                prever[tmp.to] = currentEdge.to;
                pq.push(Edge(tmp.to, cost[tmp.to]));
            }
        }
    }
}
signed main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    while(cin >> w >> h, w != 0 || h != 0){
        Dijkstra<int> dj(w*h, false);
        /*
        REP(i, w*h) REP(j, w*h) dp[i][j] = (i == j ? 0 : INF);
        REP(i, h){
            REP(j, w-1){
                int x; cin >> x;
                if(x == 0){
                    dp[i*w+j][i*w+j+1] = 1;
                    dp[i*w+j+1][i*w+j] = 1;
                }
            }
            if(i < h-1){ 
                REP(j, w){
                    int x; cin >> x;
                    if(x == 0){
                        dp[i*w+j][(i+1)*w+j] = 1;
                        dp[(i+1)*w+j][i*w+j] = 1;
                    }
                }
            }
        }
        
        REP(k, w*h) REP(i, w*h) REP(j, w*h) dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j]);

        cout << (dp[0][w*h-1] == INF ? 0 : dp[0][w*h-1]+1) << endl;
        */
    
        REP(i, h){
            REP(j, w-1){
                int x; cin >> x;
                if(x == 0){
                    dj.AddEdge(i*w+j, i*w+j+1, 1);
                }
            }
            if(i < h-1){ 
                REP(j, w){
                    int x; cin >> x;
                    if(x == 0){
                        dj.AddEdge(i*w+j, (i+1)*w+j, 1);
                    }
                }
            }
        }
        dj.Run(0);
        if(dj.HasPath(w*h-1)) cout << dj.cost[w*h-1] + 1 << endl;
        else cout << 0 << endl;
    }
}



Measured memory_bytes: 3180