#include <fstream>

using namespace std;

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

#define MAX(a, b) ((a > b) ? (a) : (b))

int flip[16], flip2[16];
int mat[16][16];

int n, m, maxim = 0;

int sum() {
    int s = 0;

    for(int i = 0 ; i < 16; i++) {
        for(int j = 0; j < 16; j++) {
            s += (mat[i][j] * flip[i] * flip2[j]);
        }
    }

    return s;
}

int main()
{
    //cout << "Hello world!" << endl;

    cin >> n >> m;

    for(int i = 0 ; i < n; i++) {
        flip[i] = 1;
        for(int j = 0; j < m; j++) {
            cin >> mat[i][j];
        }
    }

    for(int i = 0; i < (1<<n); i++) {
        for(int k = 0; k < (1<<m); k++) {
            for(int j = 0; j < n ; j++) {
                flip2[j] = ((k>>j)&1);
                if(flip2[j] == 0)
                    flip2[j] = -1;

                flip[j] = ((i>>j)&1);
                if(flip[j] == 0)
                    flip[j] = -1;
            }

            maxim = MAX(maxim, sum());
        }
    }

    cout << maxim;

    return 0;
}