#include <fstream>
using namespace std;

const int MAXN = 17;
const int INF = 1 << 30;

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

int rasp = -INF;
int v[MAXN][MAXN];
int n,m;

int solcol[MAXN], sollin[MAXN];



void bkt(int poz, int v[], int lim, void (*raspuns)())
{
    if (poz > lim)
    {
        raspuns();
        return;
    }
    v[poz] = -1;
    bkt(poz + 1, v, lim, raspuns);
    v[poz] = 1;
    bkt(poz + 1, v, lim, raspuns);
}

void raspuns_2()
{
    int sum = 0;
    for (int i = 1;i <= n;++i)
        for (int j = 1;j <= m;++j)
            sum += v[i][j] * sollin[i] * solcol[j];
    if (sum > rasp)
        rasp = sum;
}

void raspuns_1()
{
    bkt(1,solcol,m,raspuns_2);
}

void citire()
{
    in >> n >> m;
    for (int i = 1;i <= n;++i)
        for (int j = 1;j <= m;++j)
            in >> v[i][j];
}

int main()
{
    citire();
    bkt(1,sollin,n,raspuns_1);
    out << rasp << '\n';
    return 0;
}