#include <fstream>

using namespace std;

int a[17][17], x[34], n, m, maxim, cmax, suma;

void flip() {
    int i, j, b[17][17], s;

    cmax = suma;

    for ( i = 1; i <= n; i++ )
        for( j = 1; j <= m; j++ )
            b[i][j] = a[i][j];

    for ( i = 1; i <= n; i++ ) {
        if ( x[i] == 1 ) {
            for ( j = 1; j <= m; j++ ) {
                cmax = cmax - 2*b[i][j];
                b[i][j] = -b[i][j];
            }
        }
    }

    for ( j = 1; j <= m; j++ ) {
        s = 0;
        for ( i = 1; i <= n; i++ )
            s = s + b[i][j];
        if ( s < 0 )
            for ( i = 1; i <= n; i++ ) {
                cmax = cmax - 2*b[i][j];
                b[i][j] = -b[i][j];
            }
    }
}

void back(int k) {
    for ( int i = 0; i <= 1; i++ )
        if ( k == n ) {
            x[k] = i;
            flip();
            if ( cmax > maxim )
                maxim = cmax;
        }
        else {
            x[k] = i;
            back(k+1);
        }
}

int main()
{

    ifstream f("flip.in");
    f >> n >> m;

    int i, j;
    for ( i = 1; i <= n; i++ )
        for( j = 1; j <= m; j++ )
            {
                f >> a[i][j];
            }
    for ( i = 1; i <= n; i++ )
        for( j = 1; j <= m; j++ )
            {
                maxim = maxim + a[i][j];
            }
    f.close();

    cmax = maxim;
    suma = cmax;

    back(1);

    ofstream g("flip.out");

    g<<maxim;

    g.close();

    return 0;
}