#include <fstream>
#include <iostream>
#include <cstdlib>
using namespace std;

long tabla[17][17]; //tabla de joc
unsigned int n,m;   //dimensiunile tablei de joc
long long smax = 0;

void ReadData ()
{
    register unsigned int i,j;  //contoare rapide
    
    //citim fisierul de intrare
    fstream fin("flip.in", ios::in);
    fin >> n;
    fin >> m;
    for ( i = 0; i < n; ++i )
        for ( j = 0; j < m; ++j )
        {
           fin >> tabla[i][j];
        }
    fin.close();
}
void WriteData ()
{
    fstream fout("flip.out", ios::out);
    fout << smax;
    fout.close();
}
void ShowData ()
{
    register unsigned int i,j;
    for ( i = 0; i < n; ++i )
    {
      for ( j = 0; j < m; ++j )
      {
         cout << tabla[i][j] << " ";
      }
      cout << endl << endl;
    }
}

long long SumRow (unsigned int i)
{
     long long s = 0;
     register unsigned int j;
     for (j = 0; j < m; j++)
     {      
           s += tabla[i][j];
     }
     return s;
}

long long SumColumn (unsigned int j)
{
     long long s = 0;
     register unsigned int i;
     for (i = 0; i < n; i++)
     {      
           s += tabla[i][j];
     }
     return s;
}

void FlipColumn (unsigned int j)
{
     register unsigned int i;
     for (i = 0; i < m; i++)
     {
         tabla[i][j] *= -1;
     }
}

void FlipRow (unsigned int i)
{
     register unsigned int j;
     for (j = 0; j < n; j++)
     {
         tabla[i][j] *= -1;
     }
}

void FlipMatrix ()
{
     register unsigned int i,j;
     
     bool ok;
     
     do
     {
          ok = true;
          for (i = 0; i < n; i++)
          {
              long long sr = SumRow (i);
              if (sr < 0) 
              {
                  ok = false;
                  FlipRow (i);
              }
          }
          for (j = 0; j < n; j++)
          {
              long long sc = SumColumn (j);
              if (sc < 0) 
              {
                  ok = false;
                  FlipColumn (j);
              }
          }          
          
     } while (!ok)
     
     for (i = 0; i < n; i++)
     {
       for (j = 0; j < m; j++)
       {
           smax += tabla[i][j];
       }
     }
}

int main(void)
{      
    ReadData ();
    ShowData ();
    FlipMatrix ();
    WriteData ();
    
    return(0);
}