#include<fstream>
using namespace std;
int v[1000][1000],s1,s2,s,m,n;
void citire()
{int i,j;
     ifstream fin("flip.in");
     fin>>n>>m;
     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 rezolvare()
    {int i,j,gasit=0;
    ofstream fout("flip.out");
     while(gasit==0)
     {gasit=1;
     for(j=1;j<=n;j++)
       if(v[j][0]<0)
         {v[j][0]*=-1;
         for(i=1;i<=m;i++)
         {v[j][i]*=-1;v[0][i]+=2*v[j][i];gasit=0;}}
     for(j=1;j<=m;j++)
      if(v[0][j]<0)
        {v[0][j]*=-1; 
        for(i=1;i<=n;i++)
         {v[i][j]*=-1;v[0][j]+=2*v[i][j];gasit=0;}}
          for(j=1;j<=n;j++)
       if(v[j][0]<0)
         {v[j][0]*=-1;
         for(i=1;i<=m;i++)
         {v[j][i]*=-1;v[0][i]+=2*v[j][i];gasit=0;}}
} 
for(j=1;j<=n;j++)
for(i=1;i<=m;i++)
s+=v[j][i];
        fout<<s;
         fout.close();
         }
     int main()
     {citire();
         rezolvare();
         return 0;}