#include<stdio.h>
FILE *f=fopen("flip.in","r"),
     *g=fopen("flip.out","w");
long n,m,i,j,a[17][17],t,b[17][17],s,sm;
void verl()
{ for(i=1;i<=n;++i) { s=0;
		      for(j=1;j<=m;++j) s+=b[i][j];
		      if(s<0) for(j=1;j<=m;++j) b[i][j]=-b[i][j];
		    }
}
void verc()
{ for(i=1;i<=m;++i) { s=0;
		      for(j=1;j<=n;++j) s+=b[j][i];
		      if(s<0) for(j=1;j<=n;++j) b[j][i]=-b[j][i];
		    }
}
void cop()
{ for(i=1;i<=n;++i) for(j=1;j<=m;++j) b[i][j]=a[i][j];
}
long ver()
{ s=0;
  for(i=1;i<=n;++i) for(j=1;j<=m;++j) s+=b[i][j];
   return s;
}
int main()
{ fscanf(f,"%ld %ld",&n,&m);
  for(i=1;i<=n;++i) for(j=1;j<=m;++j) fscanf(f,"%ld",&a[i][j]);
  for(t=0;t<1<<m;++t) { cop();
			for(i=0;i<m;++i)
			   if(1<<i&t)
			       for(j=1;j<=n;++j)
				  b[j][i+1]=-b[j][i+1];
			verl();
			s=ver();
			if(s>sm) sm=s;
		      }
  for(t=0;t<1<<n;++t) { cop();
			for(i=0;i<n;++i)
			    if(1<<i&t)
				for(j=1;j<=m;++j);
				      b[i+1][j]=-b[i+1][j];
			verc();
			s=ver();
			if(s>sm) sm=s;
		      }
  fprintf(g,"%ld\n",sm);
  fclose(f);
  fclose(g);
  return 0;
}