#include <bits/stdc++.h>

#include <initializer_list>
#include <vector>

namespace nono {

template <typename T>
class Matrix {
  public:
    Matrix() = default;
    Matrix(int row, int column): row_(row), column_(column), data_(row, std::vector<T>(column)) {}
    Matrix(int row, int column, T elem): row_(row), column_(column), data_(row, std::vector<T>(column, elem)) {}
    explicit Matrix(const std::vector<std::vector<T>>& data)
        : row_(data.size()),
          column_(data.front().size()),
          data_(data) {
        for (int i = 0; i < row_; i++) {}
    }
    Matrix(std::initializer_list<std::vector<T>> init): data_(init.begin(), init.end()) {
        row_ = data_.size();
        column_ = data_.front().size();
        for (int i = 0; i < row_; i++) {}
    }

    const std::vector<T>& operator[](const int pos) const {
        return data_[pos];
    }

    std::vector<T>& operator[](const int pos) {
        return data_[pos];
    }

    Matrix& operator+=(const T rhs) {
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                data_[i][j] += rhs;
            }
        }
        return *this;
    }

    Matrix& operator-=(const T rhs) {
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                data_[i][j] -= rhs;
            }
        }
        return *this;
    }

    Matrix& operator*=(const T rhs) {
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                data_[i][j] *= rhs;
            }
        }
        return *this;
    }

    Matrix& operator/=(const T rhs) {
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                data_[i][j] /= rhs;
            }
        }
        return *this;
    }

    friend Matrix operator+(const Matrix& lhs, const T rhs) {
        return Matrix(lhs) += rhs;
    }
    friend Matrix operator+(const T lhs, const Matrix& rhs) {
        return Matrix(rhs) += lhs;
    }
    friend Matrix operator-(const Matrix& lhs, const T rhs) {
        return Matrix(lhs) -= rhs;
    }
    friend Matrix operator-(const T lhs, const Matrix& rhs) {
        return Matrix(rhs) -= lhs;
    }
    friend Matrix operator*(const Matrix& lhs, const T rhs) {
        return Matrix(lhs) *= rhs;
    }
    friend Matrix operator*(const T lhs, const Matrix& rhs) {
        return Matrix(rhs) *= lhs;
    }
    friend Matrix operator/(const Matrix& lhs, const T rhs) {
        return Matrix(lhs) /= rhs;
    }
    friend Matrix operator/(const T lhs, const Matrix& rhs) {
        return Matrix(rhs) /= lhs;
    }

    Matrix& operator+=(const Matrix& rhs) {
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                data_[i][j] += rhs.data_[i][j];
            }
        }
        return *this;
    }

    Matrix& operator-=(const Matrix& rhs) {
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                data_[i][j] -= rhs.data_[i][j];
            }
        }
        return *this;
    }

    Matrix& operator*=(const Matrix& rhs) {
        std::vector<std::vector<T>> mat(row_, std::vector<T>(rhs.column_));
        for (int i = 0; i < row_; i++) {
            for (int k = 0; k < column_; k++) {
                for (int j = 0; j < rhs.column_; j++) {
                    mat[i][j] += data_[i][k] * rhs.data_[k][j];
                }
            }
        }
        data_ = std::move(mat);
        column_ = rhs.column_;
        return *this;
    }

    friend Matrix operator+(const Matrix& lhs, const Matrix& rhs) {
        return Matrix(lhs) += rhs;
    }
    friend Matrix operator-(const Matrix& lhs, const Matrix& rhs) {
        return Matrix(lhs) -= rhs;
    }
    friend Matrix operator*(const Matrix& lhs, const Matrix& rhs) {
        return Matrix(lhs) *= rhs;
    }

    [[nodiscard]] Matrix pow(long long exp) const {
        Matrix result(row_, column_);
        Matrix base(*this);
        for (int i = 0; i < row_; i++) {
            result[i][i] = static_cast<T>(1);
        }
        while (exp > 0) {
            if (exp & 1) {
                result *= base;
            }
            base *= base;
            exp >>= 1;
        }
        return result;
    }

    [[nodiscard]] Matrix rotate() {
        std::vector<std::vector<T>> result(column_, std::vector<T>(row_));
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                result[j][row_ - i - 1] = data_[i][j];
            }
        }
        return Matrix(result);
    }

    [[nodiscard]] Matrix transpose() {
        std::vector<std::vector<T>> result(column_, std::vector<T>(row_));
        for (int i = 0; i < row_; i++) {
            for (int j = 0; j < column_; j++) {
                result[j][i] = data_[i][j];
            }
        }
        return Matrix(result);
    }

    int row() {
        return row_;
    }

    int column() {
        return column_;
    }

  private:
    int row_, column_;
    std::vector<std::vector<T>> data_;
};

}  //  namespace nono

namespace nono {

struct Init {};

void solve([[maybe_unused]] const Init& init) {
    int h, w;
    std::cin >> h >> w;
    Matrix<int> a(h, w);
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            std::cin >> a[i][j];
        }
    }

    int ans = 0;

    std::vector<int> row(h);
    std::vector<int> column(h);
    std::vector<int> naname1(h + w - 1);
    std::vector<int> naname2(h + w - 1);

    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            row[i] += a[i][j];
            column[j] += a[i][j];
            naname1[i + j] += a[i][j];
            naname2[h - 1 - i + j] += a[i][j];
        }
    }

    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            ans = std::max(ans, row[i] + column[j] - a[i][j]);
        }
    }

    for (int i = 0; i < h; i++) {
        for (int k = 0; k + 1 < h + w - 1; k++) {
            int j = k - i;
            if (0 <= j && j < w) {
                ans = std::max(ans, row[i] + naname1[k] - a[i][j]);
            } else {
                ans = std::max(ans, row[i] + naname1[k]);
            }
        }
    }

    for (int i = 0; i < h; i++) {
        for (int k = 0; k + 1 < h + w - 1; k++) {
            int j = k - h + 1 + i;
            if (0 <= j && j < w) {
                ans = std::max(ans, row[i] + naname2[k] - a[i][j]);
            } else {
                ans = std::max(ans, row[i] + naname2[k]);
            }
        }
    }

    for (int j = 0; j < w; j++) {
        for (int k = 0; k + 1 < h + w - 1; k++) {
            int i = k - j;
            if (0 <= i && i < h) {
                ans = std::max(ans, column[j] + naname1[k] - a[i][j]);
            } else {
                ans = std::max(ans, column[j] + naname1[k]);
            }
        }
    }

    for (int j = 0; j < w; j++) {
        for (int k = 0; k + 1 < h + w - 1; k++) {
            int i = h - 1 + j - k;
            if (0 <= i && i < h) {
                ans = std::max(ans, column[j] + naname1[k] - a[i][j]);
            } else {
                ans = std::max(ans, column[j] + naname1[k]);
            }
        }
    }

    for (int k1 = 0; k1 + 1 < h + w - 1; k1++) {
        for (int k2 = 0; k2 + 1 < h + w - 1; k2++) {
            bool flag = false;
            if ((k1 + k2 - h + 1) % 2 == 0) {
                int j = (k1 + k2 - h + 1) / 2;
                int i = k1 - j;
                if (0 <= i && i < h && 0 <= j && j < w) {
                    flag = true;
                    ans = std::max(ans, naname1[k1] + naname2[k2] - a[i][j]);
                }
            }
            if (!flag) {
                ans = std::max(ans, naname1[k1] + naname2[k2]);
            }
        }
    }

    std::ranges::sort(row, std::greater());
    std::ranges::sort(column, std::greater());
    std::ranges::sort(naname1, std::greater());
    std::ranges::sort(naname2, std::greater());

    ans = std::max(ans, row[0]);
    ans = std::max(ans, column[0]);
    ans = std::max(ans, naname1[0]);
    ans = std::max(ans, naname2[0]);
    if (row.size() > 1) ans = std::max(ans, row[0] + row[1]);
    if (column.size() > 1) ans = std::max(ans, column[0] + column[1]);
    if (naname1.size() > 1) ans = std::max(ans, naname1[0] + naname1[1]);
    if (naname2.size() > 1) ans = std::max(ans, naname2[0] + naname2[1]);

    std::cout << ans << std::endl;
}

}  //  namespace nono

int main() {
    std::cin.tie(0)->sync_with_stdio(0);
    std::cout << std::fixed << std::setprecision(16);

    int t = 1;
    nono::Init init;

    while (t--) nono::solve(init);
}