#include <fstream>

using namespace std;

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

int main()
{
    int n, m, i, j, Scopie, Stotal = 0;
    fin >> n >> m;
    int matrix[n][m];
    for (i=0;i<n;i++)
        for (j=0;j<m;j++)
        {
            fin >> matrix[i][j];
            Stotal += matrix[i][j];
        }
    for (i=n-1;i>=0;i--)
    {
        Scopie = Stotal;
        for (j=m-1;j>=0;j--)
            Scopie += (-1)* matrix[i][j] - matrix[i][j];
        if (Scopie > Stotal)
        {
            Stotal = Scopie;
                for (j=m-1;j>=0;j--)
                    matrix[i][j] = -matrix[i][j];
        }
    }
    for (j=0;j<m;j++)
    {
        Scopie = Stotal;
        for (i=0;i<n;i++)
            Scopie += (-1)* matrix[i][j] - matrix[i][j];
        if (Scopie > Stotal)
        {
            Stotal = Scopie;
                for (i=0;i<n;i++)
                    matrix[i][j] = -matrix[i][j];
        }
    }
    gout << Stotal;
    return 0;
}