#include <fstream>
#include <cmath>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int n,m;
long long a[17][17];
void citire()
{f>>n>>m;
 int i,j;
 for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)f>>a[i][j];
}
void trans_1(long long a[17][17])
{long long  s,i,j;
 for(j=1;j<=m;j++)
 {s=0;
  for(i=1;i<=n;i++)s+=a[i][j];
  if(s<0)
  for(i=1;i<=n;i++)a[i][j]*=-1;
 }
}
void trans_2(long long a[17][17])
{int i,j;
 long long  s;
 for(i=1;i<=n;i++)
 {s=0;
  for(j=1;j<=m;j++)s+=a[i][j];
  if(s<0)
    for(j=1;j<=m;j++)a[i][j]*=-1;
 }
}
void suma(long long a[17][17])
{int i,j;
  long long  s=0;
 for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)s=s+abs(a[i][j]);
  g<<s;
}
int main()
{int i,j;
 citire();
 trans_1(a);
 trans_2(a);
 suma(a);
    return 0;
}