#include <fstream>
using namespace std;

    ifstream f ("flip.in");
    ofstream g ("flip.out");
int main()
{
  int a[100][100],n,m,smax,smax2;
  f>>n>>m;
  for(int i=1;i<=n;++i)
   {    smax = smax2 = 0;
        for(int j=1;j<=m;++j)
        {
            f>>a[i][j];
            smax+=a[i][j];
            smax2+=-1*a[i][j];
        }
        if(smax<smax2) for(int j=1;j<=n;++j) a[i][j]*=-1;
   }
   for(int i=1;i<=n;++i)
   {
       smax = smax2 = 0;
       for(int j=1;j<=n;++j)
            {
                smax+=a[j][i];
                smax2+=-1*a[j][i];
            }
       if(smax<smax2) for(int j=1;j<=n;++j) a[j][i]*=-1;
   }
   smax = 0;

   for(int i=1;i<=n;++i)
    for(int j=1;j<=n;++j)
      smax+=a[i][j];

   g<<smax;
   f.close();
   g .close();
    return 0;
}