#include <fstream>
using namespace std;

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

int n, m, a[16][16], s;

void gen(int k)
{
    if (k == m)
    {
        int s2 = 0, i, j, saux;
        for (i = 0; i<n; i++)
        {
            saux = 0;
            for (j = 0; j<m; j++)
                saux = saux + a[i][j];
            if (saux < 0)
                saux = (-1)*saux;
            s2 = s2 + saux;
        }
        if (s2 > s)
            s = s2;
    }
    else
    {
        gen(k+1);
        for (int i = 0; i<n; i++)
            a[i][k] = (-1)*a[i][k];
        gen(k+1);
    }
}

int main()
{
    int i, j;
    fin >> n >> m;
    for (i = 0; i<n; i++)
        for (j = 0; j<m; j++)
        {
            fin >> a[i][j];
            s = s + a[i][j];
        }
    gen(0);
    fout << s;
}