# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
template<class T> bool is_sqare(T a) { if(floor(sqrt(a)) * floor(sqrt(a)) == a){ return true; }return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        sort(all((wpwpw)));(wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((int)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
#ifdef LOCAL
#  include "_debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

struct INIT{
    INIT(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(0);
        cout << fixed << setprecision(20);
    }
}INIT;

void solve(){
    int h, w;
    cin >> h >> w;
    vector<vector<int>> a(h + 2, vector<int>(w + 2));
    reps(i, h)reps(j, w)cin >> a[i][j];
    ll ans = 0;
    const int dy[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
    const int dx[8] = {0, 1, 1, 1, 0, -1, -1, -1};
    auto within = [&](int y, int x) -> bool {
        return 0 <= y && y < h + 2 && 0 <= x && x < w + 2;
    };
    
    vector<pair<int, int>> edge;
    rep(i, h + 1){
        edge.push_back({i, 0});
        edge.push_back({i, w + 1});
    }
    rep(j, w + 1){
        edge.push_back({0, j});
        edge.push_back({h + 1, j});
    }
    sort(all(edge));
    UNIQUE(edge);

    for(auto [uy, ux] : edge) {
        rep(dir1, 8){
            set<pair<int, int>> st;
            {
                int y = uy, x = ux;
                while(within(y, x)){
                    st.insert({y, x});
                    y += dy[dir1];
                    x += dx[dir1];
                }
            }
            ll cur = 0;
            for(auto [y, x] : st){
                cur += a[y][x];
            }
            for(auto [vy, vx] : edge) {
                rep(dir2, 8){
                    set<pair<int, int>> st2;
                    {
                        int y = vy, x = vx;
                        while(within(y, x)){
                            if(not st.count({y, x}))st2.insert({y, x});
                            y += dy[dir2];
                            x += dx[dir2];
                        }
                    }
                    ll cur2 = 0;
                    for(auto [y, x] : st2){
                        cur2 += a[y][x];
                    }
                    chmax(ans, cur + cur2);
                }
            }
        }
    }

    cout << ans << endl;
}

int main(){
    int t = 1;
    //cin >> t;
    while(t--)solve();
}