#include<stdio.h>
FILE *f=fopen("flip.in","r"),
     *g=fopen("flip.out","w");
int a[17][17],i,j,s,s1,m,n;
int main()
{ fscanf(f,"%d %d",&n,&m);
  for(i=1;i<=n;i++)for(j=1;j<=m;j++) fscanf(f,"%d",&a[i][j]);
  for(j=1;j<=m;j++) { s=0;
                      s1=0;
                      for(i=1;i<=n;i++) { s=s+a[i][j];
                                          s1=s1-a[i][j];
                                        }
                      if(s1>s) for(i=1;i<=n;i++) a[i][j]=-a[i][j];

                     }

  for(i=1;i<=n;i++) { s=0;
                      s1=0;
                      for(j=1;j<=m;j++) { s=s+a[i][j];
                                          s1=s1-a[i][j];
                                        }
                      if(s1>s) for(j=1;j<=m;j++) a[i][j]=-a[i][j];
                    }
  s=0;
  for(i=1;i<=n;i++)for(j=1;j<=m;j++) s=s+a[i][j];
  fprintf(g,"%d",s);
  fclose(f);
  fclose(g);
  return 0;
}