#include<iostream>
#include<fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int n,m,a[16][16],i,j,s1,s2,s3,s4,s;
void sum()
{s=0;
  for(j=1;j<=m;j++)
  {
      s1=s2=s3=s4=0;

        for(i=1;i<=n;i++)
        {s1=s1+a[i][j];
        s2=s2+a[i][j]*-1;
        if(i<=m)
           s3=s3+a[j][i];
            s4=s4+a[j][i]*-1;
          }
        if(s1<s2)
            {for(i=1;i<=n;i++)
            a[i][j]=a[i][j]*-1;}
            if(s3<s4)
            {for(i=1;i<=n;i++)
         a[j][i]=a[j][i]*-1;}
         }
}

     void maxx()

     {
        sum();
    for(i=1;i<=n;i++)
    {for(j=1;j<=m;j++)
    s=s+a[i][j];}
     }
int main()
{
f>>n>>m;
for(i=1;i<=n;i++)
    {for(j=1;j<=m;j++)
    f>>a[i][j];}
maxx();
g<<s;







return 0;}