#include <fstream>
using namespace std;
int main()
{
    ifstream ii("flip.in");
    ofstream oo("flip.out");
    unsigned short n, m, i, j, k, l;
    ii >> n >> m;
    long a[n][m], s = 0, ss;  short v[n], w[n];
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < m; j++)
            ii >> a[i][j];
        v[i] = 0;
    }
    for (i = 0; i < m; i++)
        w[i] = 0;
    i = 0;  j = 0;
    while (i < n)
    {
        i = 0;
        while (v[i] && i < n)
        {
            v[i] = 0;  i++;
        }
        if (i == n)  break;
        v[i] = 1;
        while (j < m)
        {
            j = 0;
            while (w[j] && j < m)
            {
                w[j] = 0;  j++;
            }
            if (j == m)  break;
            w[j] = 1;  ss = 0;
            for (k = 0; k < n; k++)
                for (l = 0; l < m; l++)
                    if (v[k] == w[l])
                        ss += a[k][l];
                    else
                        ss -= a[k][l];
            if (ss > s)  s = ss;
        }
    }
    oo << s;
    ii.close();  oo.close();
}