#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("flip.in");
ofstream fout("flip.out");

int v[16][16], n, m, i, j, maxi = 0;

int sumaa()
{
    int s = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            s += v[i][j];

    return s;
}

void modif(int i, int j)
{
    for (int k = 0; k < n; k++)
        if (k != i)
            v[k][j] *= -1;
    for (int k = 0; k < m; k++)
        if (k != j)
            v[i][k] *= -1;
}

void bkt(int i, int j)
{
    if (i == n)
    {
        if (maxi < sumaa())
            maxi = sumaa();
    }
    else
    {
        for (int k = 1; k <= 2; k++)
        {
            modif(i, j);

            if (j == m - 1)
                bkt(i + 1, 1);
            else
                bkt(i, j + 1);
        }
    }
}

int main()
{
    fin >> n >> m;

    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            fin >> v[i][j];

    bkt(0, 0);

    fout << maxi;

    return 0;
}