program e2;

var
	f_in,f_out:text;
	a:array[1..16,1..16] of longint;
	i,j,n,m:word;
	s,s_init:longint;
	
begin
	i:=0; j:=0; n:=0; m:=0; s:=0; s_init:=0;

	assign(f_in,'flip.in');
	assign(f_out,'flip.out');
	reset(f_in); rewrite(f_out);
	
	readln(f_in,n,m);
	for i:=1 to n do begin
		for j:=1 to m do
			read(f_in,a[i,j]);
		readln(f_in); end;
	
	//schimba coloanele unde e cazul
	for j:=1 to m do begin
		for i:=1 to n do begin
			s_init:=s_init+a[i,j];
			s:=s+a[i,j]*(-1); end;
		if (s>s_init) then
			for i:=1 to n do
				a[i,j]:=a[i,j]*(-1);
		s:=0; s_init:=0; end;
		
	s:=0; s_init:=0;
	//schimba liniile unde e cazul	
	for i:=1 to n do begin
		for j:=1 to m do begin
			s_init:=s_init+a[i,j];
			s:=s+a[i,j]*(-1); end;
		if (s>s_init) then
			for j:=1 to m do
				a[i,j]:=a[i,j]*(-1);
		s:=0; s_init:=0; end;
	
	s:=0;
	for i:=1 to n do
		for j:=1 to m do
			s:=s+a[i,j];
			
	writeln(f_out,s);
	
	close(f_in); close(f_out);	
end.