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

class Board {
private:
    std::vector<std::vector<int>> internal_board;
    unsigned long long number_of_lines;
    unsigned long long number_of_columns;

public:

    explicit Board(std::vector<std::vector<int>> matrix) {
        internal_board = std::move(matrix);
        number_of_lines = internal_board.capacity();
        number_of_columns = internal_board[0].capacity();
    }

    unsigned long long get_number_of_lines(){
        return number_of_lines;
    }
    unsigned long long get_number_of_columns(){
        return number_of_columns;
    }

    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 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);

    if (!input_file.is_open()) {
        std::cerr << "Could not open the file: '" << input_file_name << "'" << std::endl;
        return EXIT_FAILURE;
    }

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

    if (!out.is_open()) {
        std::cerr << "Could not open the file: '" << output_file_name << "'" << std::endl;
        return EXIT_FAILURE;
    }

    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;
        }
    }

    input_file.close();

    auto game = new Board(matrix);

    int limit = 1 << game->get_number_of_lines();
    int max_sum = game->get_sum();

    std::vector<int> flipped_columns;
    int flipped_lines[16] = {0};

    auto tmp_game = game;

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

        for (int k = 0; k < tmp_game->get_number_of_columns(); ++k) {
            if (tmp_game->sum_col(k) < 0) {
                tmp_game->flip_column(k);
                flipped_columns.push_back(k);
            }
        }

        int new_sum = tmp_game->get_sum();
        if (new_sum > max_sum) {
            max_sum = new_sum;
        }

        while (!flipped_columns.empty()) {
            tmp_game->flip_column(flipped_columns.back());
            flipped_columns.pop_back();
        }
    }
    out << max_sum;
    out.close();
    return 0;
}

int main() {
    using namespace std;
    using namespace std::chrono;

    auto start = high_resolution_clock::now();
    flip_algo();
    auto stop = high_resolution_clock::now();
    auto duration = duration_cast<milliseconds>(stop - start);
    cout << duration.count() << endl;
}