#include <bits/stdc++.h>
#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void(0)
#endif

using namespace std;

typedef long long ll;
#define all(x) begin(x), end(x)
constexpr int INF = (1 << 30) - 1;
constexpr long long IINF = (1LL << 60) - 1;
constexpr int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

template <class T> istream& operator>>(istream& is, vector<T>& v) {
    for (auto& x : v) is >> x;
    return is;
}

template <class T> ostream& operator<<(ostream& os, const vector<T>& v) {
    auto sep = "";
    for (const auto& x : v) os << exchange(sep, " ") << x;
    return os;
}

template <class T, class U = T> bool chmin(T& x, U&& y) { return y < x and (x = forward<U>(y), true); }

template <class T, class U = T> bool chmax(T& x, U&& y) { return x < y and (x = forward<U>(y), true); }

template <class T> void mkuni(vector<T>& v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <class T> int lwb(const vector<T>& v, const T& x) { return lower_bound(begin(v), end(v), x) - begin(v); }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int H, W;
    cin >> H >> W;
    vector A(H, vector<int>(W));
    cin >> A;

    ll ans = 0;
    vector<pair<int, int>> ex;
    for (int i = -1; i <= H; i++) {
        for (int j = -1; j <= W; j++) {
            if (i == -1 or i == H or j == -1 or j == W) {
                ex.emplace_back(i, j);
            }
        }
    }
    vector check(H, vector<bool>(W, false));
    for (int i = 0; i < int(ex.size()); i++) {
        for (int j = i; j < int(ex.size()); j++) {
            for (int dx1 = -1; dx1 <= 1; dx1++) {
                for (int dy1 = -1; dy1 <= 1; dy1++) {
                    if (dx1 == 0 and dy1 == 0) continue;
                    for (int dx2 = -1; dx2 <= 1; dx2++) {
                        for (int dy2 = -1; dy2 <= 1; dy2++) {
                            if (dx2 == 0 and dy2 == 0) continue;
                            ll sum = 0;
                            {
                                auto [x, y] = ex[i];
                                while (true) {
                                    x += dx1, y += dy1;
                                    if (x < 0 or H <= x or y < 0 or W <= y) break;
                                    if (not check[x][y]) sum += A[x][y];
                                    check[x][y] = true;
                                }
                            }
                            {
                                auto [x, y] = ex[j];
                                while (true) {
                                    x += dx2, y += dy2;
                                    if (x < 0 or H <= x or y < 0 or W <= y) break;
                                    if (not check[x][y]) sum += A[x][y];
                                    check[x][y] = true;
                                }
                            }
                            chmax(ans, sum);
                            {
                                auto [x, y] = ex[i];
                                while (true) {
                                    x += dx1, y += dy1;
                                    if (x < 0 or H <= x or y < 0 or W <= y) break;
                                    check[x][y] = false;
                                }
                            }
                            {
                                auto [x, y] = ex[j];
                                while (true) {
                                    x += dx2, y += dy2;
                                    if (x < 0 or H <= x or y < 0 or W <= y) break;
                                    check[x][y] = false;
                                }
                            }
                        }
                    }
                }
            }
        }
    }

    cout << ans << '\n';
    return 0;
}