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

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return vector(arg, init);
    else return vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename Container>
auto distance(const Container &c, decltype(begin(c)) iter) {
    return distance(begin(c), iter);
}

template <typename RIter, typename Compare = less<typename iterator_traits<RIter>::value_type>>
auto isort(RIter first, RIter last, Compare comp = Compare()) {
    vector<int> i(distance(first, last));
    iota(begin(i), end(i), 0);
    sort(begin(i), end(i), [&](auto x, auto y) {
        return comp(*(first + x), *(first + y));
    });
    return i;
}

template <typename, template <typename> typename, typename = void_t<>>
struct detect : false_type {};
template <typename T, template <typename> typename Check>
struct detect<T, Check, void_t<Check<T>>> : true_type {};
template <typename T, template <typename> typename Check>
constexpr inline bool detect_v = detect<T, Check>::value;

template <typename T>
using has_member_sort = decltype(declval<T>().sort());

template <typename Container, typename Compare = less<typename Container::value_type>>
auto sorted(Container c, Compare comp = Compare()) {
    if constexpr (detect_v<Container, has_member_sort>) {
        c.sort(comp);
        return c;
    }
    else {
        sort(begin(c), end(c), comp);
        return c;
    }
}

template <typename Container, typename Compare = equal_to<typename Container::value_type>>
auto uniqued(Container c, Compare comp = Compare()) {
    c.erase(unique(begin(c), end(c), comp), end(c));
    return c;
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

template <typename F>
constexpr auto fix(F &&f) noexcept {
    return [f = std::tuple<F>(std::forward<F>(f))](auto &&...args) mutable {
        return std::get<0>(f)(fix(std::get<0>(f)), std::forward<decltype(args)>(args)...);
    };
}

int main() {
    int h, w; cin >> h >> w;

    auto a = vec<int>(uns, h, w);
    for (auto &r : a) {
        for (auto &e : r) {
            cin >> e;
        }
    }

    auto b = vec<int>(uns, h + w - 1, h + w - 1);
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            b[w - 1 + i - j][i + j] = a[i][j];
        }
    }

    auto f = [](int h, int w, const auto &v) {
        int ans = 0;

        for (int i = 0; i < h; ++i) {
            int x = 0;
            for (int k = 0; k < w; ++k) {
                x += v[i][k];
            }
            chmax(ans, x);

            for (int j = i + 1; j < h; ++j) {
                int y = 0;
                for (int k = 0; k < w; ++k) {
                    y += v[j][k];
                }
                chmax(ans, x + y);
            }
        }

        return ans;
    };

    auto g = [](int h, int w, const auto &v) {
        auto r = vec<int>(uns, h);
        auto c = vec<int>(uns, w);

        for (int i = 0; i < h; ++i) {
            int sum = 0;
            for (int j = 0; j < w; ++j) {
                sum += v[i][j];
            }
            r[i] = sum;
        }

        for (int i = 0; i < w; ++i) {
            int sum = 0;
            for (int j = 0; j < h; ++j) {
                sum += v[j][i];
            }
            c[i] = sum;
        }

        int ans = 0;

        for (int i = 0; i < h; ++i) {
            for (int j = 0; j < w; ++j) {
                chmax(ans, r[i] + c[j] - v[i][j]);
            }
        }

        return ans;
    };

    auto s = [](int h, int w, const auto &v) {
        auto r = vec<int>(uns, h);

        for (int i = 0; i < h; ++i) {
            int sum = 0;
            for (int j = 0; j < w; ++j) {
                sum += v[i][j];
            }
            r[i] = sum;
        }

        int ans = 0;
        for (int i = 0; i < h; ++i) {
            for (int j = 0; j < w; ++j) {
                int d1 = min(i, j);
                int d2 = min(i, w - j - 1);

                int sum1 = 0;
                for (int k = 0; i - d1 + k < h && j - d1 + k < w; ++k) {
                    sum1 += v[i - d1 + k][j - d1 + k];
                }

                int sum2 = 0;
                for (int k = 0; i - d2 + k < h && 0 <= j + d2 - k; ++k) {
                    sum2 += v[i - d2 + k][j + d2 - k];
                }

                chmax(ans, r[i] + max(sum1, sum2) - v[i][j]);
            }
        }

        return ans;
    };

    auto rot = [](int h, int w, const auto &v) {
        auto u = vec<int>(uns, w, h);
        for (int i = 0; i < h; ++i) {
            for (int j = 0; j < w; ++j) {
                u[j][h - i - 1] = v[i][j];
            }
        }
        return u;
    };

    int ans = 0;

    chmax(ans, f(h, w, a));
    chmax(ans, f(w, h, rot(h, w, a)));
    chmax(ans, f(h + w - 1, h + w - 1, b));
    chmax(ans, f(h + w - 1, h + w - 1, rot(h + w - 1, h + w - 1, b)));

    chmax(ans, g(h, w, a));
    chmax(ans, g(h + w - 1, h + w - 1, b));

    chmax(ans, s(h, w, a));
    chmax(ans, s(w, h, rot(h, w, a)));

    cout << ans << endl;
}