#include <bits/stdc++.h>
using namespace std;

#define rep(i, m, n) for(int(i) = (int)(m); i < (int)(n); ++i)
#define rep2(i, m, n) for(int(i) = (int)(n)-1; i >= (int)(m); --i)
#define REP(i, n) rep(i, 0, n)
#define REP2(i, n) rep2(i, 0, n)
#define all(hoge) (hoge).begin(), (hoge).end()
#define en '\n'
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template <class T>
using vec = vector<T>;
template <class T>
using vvec = vector<vec<T>>;
typedef pair<ll, ll> P;
constexpr long long INF = 1LL << 60;
constexpr int INF_INT = 1 << 25;
constexpr long long MOD = (ll)1e9 + 7;
//constexpr long long MOD = 998244353LL;
using ld = long double;
static const ld pi = 3.141592653589793L;
typedef vector<ll> Array;
typedef vector<Array> Matrix;

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

struct Edge {
    ll to, rev;
    long double cap;
    Edge(ll _to, long double _cap, ll _rev) {
        to = _to;
        cap = _cap;
        rev = _rev;
    }
};
using Edges = vector<Edge>;
using Graph = vector<Edges>;

void add_edge(Graph &G, ll from, ll to, long double cap, bool revFlag,
              long double revCap) {
    G[from].push_back(Edge(to, cap, (ll)G[to].size()));
    if(revFlag)
        G[to].push_back(Edge(from, revCap, (ll)G[from].size() - 1));
}

void solve() {
    int w, h;
    while(cin >> w >> h) {
        if(w == 0 and h == 0)
            break;
        Matrix a(2 * h, Array(2 * w, 0));
        REP(i, h) {
            REP(j, w - 1) {
                ll aa;
                cin >> aa;
                if(aa) {
                    a[i * 2][j * 2 + 1] = 1;
                    a[i * 2 + 1][j * 2 + 1] = 1;
                }
            }
            if(i == h - 1)
                break;
            REP(j, w) {
                ll aa;
                cin >> aa;
                if(aa) {
                    a[i * 2 + 1][j * 2] = 1;
                    a[i * 2 + 1][j * 2 + 1] = 1;
                }
            }
        }
        queue<P> que;
        Matrix d(2 * h, Array(2 * w, 0));
        que.push({0, 0});
        d[0][0] = 1;
        int dx[4] = {0, 0, 2, -2};
        int dy[4] = {2, -2, 0, 0};

        while(que.size()) {
            int y = que.front().first;
            int x = que.front().second;
            //cout << y << " " << x << en;
            que.pop();
            REP(v, 4) {
                int ny = y + dy[v];
                int nx = x + dx[v];
                if(ny < 0 or ny >= 2 * h or nx < 0 or nx >= 2 * w)
                    continue;
                if(a[(ny + y) / 2][(nx + x) / 2] or a[ny][nx])
                    continue;
                if(d[ny][nx])
                    continue;
                d[ny][nx] = d[y][x] + 1;
                que.push({ny, nx});
            }
        }
        cout << d[2 * (h - 1)][2 * (w - 1)] << en;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    solve();

    /*
    ll t;
    cin >> t;
    REP(i, t) { solve();}
    */

    return 0;
}



Measured memory_bytes: 3240