#include <fstream>

using namespace std;

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

int main()
{
    int a[17][17], m, n;
    fin >> n >> m;

    for (int i = 1; i<=n; i++)
        for (int j = 1; j<=m; j++)
            fin >> a[i][j];


    int s;
    for (int i = 1; i<=n; i++)
    {
        s =0;
        for (int j = 1; j<=m; j++)s+=a[i][j];

        if (s < 0)
            for (int j = 1; j<=m; j++)a[i][j]*=-1;
    }
    int st =0;
    for (int j = 1; j<=m; j++)
    {
        s =0;
        for (int i = 1; i<=n; i++)s+=a[i][j];

        if (s < 0)
        {
            for (int i = 1; i<=m; i++)a[i][j]*=-1;
            st+=s * -1;
        }
        else st+=s;
    }
    /*for (int i = 1; i<=n; i++)
    {
        for (int j = 1; j<=m; j++)
            fout << a[i][j] << ' ';
        fout << '\n';
    }*/
    fout << st;
    return 0;
}