#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

enum Direction {
    positive, negative
};

class Board {
private:
    std::vector<std::vector<int>> internal_board;
    Direction line_direction[16] = {positive};
    Direction column_direction[16] = {positive};

public:
    explicit Board(std::vector<std::vector<int>> matrix) {
        internal_board = std::move(matrix);
    }

    Board(const Board &board1) {
        internal_board = board1.internal_board;
    }

    void flip_line(int number) {
        for (auto &col: internal_board[number]) {
            col *= -1;
        }
    }

    void flip_column(int number) {
        for (auto &row: internal_board) {
            row[number] *= -1;
        }
    }

    void flip_line(int number, Direction direction) {
        if (direction != line_direction[number]) {
            line_direction[number] = direction;
            flip_line(number);
        }
    }

    void flip_column(int number, Direction direction) {
        if (direction != column_direction[number]) {
            column_direction[number] = direction;
            flip_column(number);
        }
    }

    void print_matrix() {
        std::cout << "\n<------------------->\n";

        for (const auto &row: internal_board) {
            for (const auto &col: row) {
                std::cout << col << " ";
            }
            std::cout << '\n';
        }
    }

    int get_sum() {
        int sum = 0;

        for (const auto &row: internal_board) {
            for (const auto &col: row) {
                sum += col;
            }
        }

        return sum;
    }

    int sum_line(int number) {
        int sum = 0;

        for (const auto &col: internal_board[number]) {
            sum += col;
        }

        return sum;
    }

    int sum_col(int number) {
        int sum = 0;

        for (const auto &row: internal_board) {
            sum += row[number];
        }

        return sum;
    }

    void print_sum() {
        std::cout << '\n' << get_sum() << '\n';
    }
};

int flip_algo() {
    std::string input_file_name("../flip.in");
    std::string output_file_name("../flip.out");

    std::ifstream input_file;
    input_file.open(input_file_name);

    int M, N;
    input_file >> M >> N;

    auto matrix = std::vector<std::vector<int>>(M);

    for (auto &row: matrix) {
        row = std::vector<int>(N);

        for (auto &col: row) {
            input_file >> col;
        }
    }

    auto game = new Board(matrix);

    int limit = 1 << M;
    int max_sum = 0;


    auto tmp_game = game;
    Direction line_direction[16] = {positive};
    Direction column_direction[16] = {positive};

    for (int i = 0; i < limit; ++i) {
        for (int j = 0; 1 << j <= i; ++j) {
            if (i & (1 << j)) {
//                tmp_game->flip_line(j, negative);
                if (line_direction[j] == positive) {
                    tmp_game->flip_line(j);
                    line_direction[j] = negative;
                }
            } else {
//                tmp_game->flip_line(j, positive);
                if (line_direction[j] == negative) {
                    tmp_game->flip_line(j);
                    line_direction[j] = positive;
                }
            }
        }

        for (int k = 0; k < N; ++k) {
            if (tmp_game->sum_col(k) < 0) {
//                tmp_game->flip_column(k, negative);
                if (column_direction[k] == positive) {
                    column_direction[k] = negative;
                    tmp_game->flip_column(k);
                }
            }
        }

        int new_sum = tmp_game->get_sum();

        if (new_sum > max_sum) {
            max_sum = new_sum;
        }

        for (int j = 0; j < N; ++j) {
//            tmp_game->flip_column(j, positive);
            if (column_direction[j] == negative) {
                column_direction[j] = positive;
                tmp_game->flip_column(j);
            }
        }
    }


    std::ofstream out;
    out.open(output_file_name);

    out << max_sum;
    return 0;
}

int main() {
    flip_algo();
}