#include <fstream>

using namespace std;

ifstream f("flip.in");
ofstream g("flip.out");

int n, m, i, j;
int a[17][17];
int smax = -2000000000;
pair < int, int > v[17];
pair < bool, bool > u[17];

void verif()
{
    int s = 0;
    for (int i=1; i<=n; i++)
        for (int j=1; j<=m; j++)
            if (u[i].first == u[j].second)
                s += a[i][j];
            else
                s -= a[i][j];
    smax = max(smax, s);
}

void bkt_col(int k)
{
    for (int i = v[k-1].second + 1; i <= m; i++)
    {
        v[k].second = i;
        u[i].second = 1;

        if (k <= n)
            verif();
        if (k < n)
            bkt_col(k + 1);

        u[i].second = 0;
    }
}

void bkt_lin(int k)
{
    for (int i = v[k-1].first + 1; i <= n; i++)
    {
        v[k].first = i;
        u[i].first = 1;

        if (k <= n)
            bkt_col(1);
        if (k < n)
            bkt_lin(k + 1);

        u[i].first = 0;
    }
}

int main()
{
    f >> n >> m;
    for (i=1; i<=n; i++)
        for (j=1; j<=m; j++)
            f >> a[i][j];

    bkt_lin(1);

    g << smax;

    return 0;
}