#include <fstream>
#include <math.h>
using namespace std;
int main()
{
    int a, A, b, n, m, i, j, k, K, l, L, x[16][16];
    A = 1;
    b = 1;
    k = 0;
    K = 0;
    ifstream fin("flip.in");
    fin >> n >> m;
    for ( i = 1; i <= n; i++ )
    {
        for ( j = 1; j <= m; j++ )
        {
            fin >> x[i][j];
            k = x[i][j] + k;
        }
    }
    fin.close();
    for ( L = 0; L <= pow(2,n) - 1; L++ )
    {
        for ( l = 0; l <= pow(2,m) - 1; l++ )
        {
            for ( i = 1; i <= n; i++ )
            {
                for ( j = 1; j <= m; j++ )
                {
                    a = x[i][j];
                    if ( L / A % 2 == 1 )
                    {
                         a = -a;
                    }
                    if ( l / b % 2 == 1 )
                    {
                         a = -a;
                    }
                    K += a;
                    b *= 2;
                }
                A *= 2;
                b = 1;
            }
            A = 1;
            if ( K > k )
            {
                 k = K;
            }
            K = 0;
        }
    }
    ofstream fout("flip.out");
    fout << k;
    fout.close();
    return 0;
}