#include<fstream>
using namespace std;
long long v[20][20];int m,n,s;
void citire()
{int i,j;
     ifstream fin("flip.in");
     fin>>m>>n;
     for(i=1;i<=n;i++)
     for(j=1;j<=m;j++)
     {fin>>v[i][j];v[i][0]+=v[i][j];v[0][j]+=v[i][j];}
     fin.close();
     }
void schimbarel(int i)
{int j;v[i][0]*=-1;
     for(j=1;j<=m;j++)
     {v[i][j]*=-1;v[0][j]+=2*v[i][j];}
     
     }
     void schimbarec(int i)
{
     int j;v[0][i]*=-1;
     for(j=1;j<=n;j++)
     {v[j][i]*=-1;v[j][0]+=2*v[j][i];}
     
     }
void verificare()
{int i,j,rezolvat(0);
     while(!rezolvat)
 {rezolvat=1;
                 for(i=1;i<=n;i++)
                 if(v[i][0]<0)
                 {schimbarel(i);rezolvat=0;}
for(i=1;i<=m;i++) 
if(v[0][i]<0)
{schimbarec(i);rezolvat=0;}
                 } 
   for(i=1;i<=n;i++)
   for(j=1;j<=m;j++)
   s+=v[i][j];   
 ofstream fout("flip.out");
 fout<<s;
 fout.close();
     }
int main()
{citire();
verificare();
    
    return 0;}