VAR
	n,m,MAX,i,j : Integer;
	v		: Array[1..16] of Longint;
	a		: Array[1..16,1..16] of Longint;
	f, g    : Text;

Procedure bkt(k : Integer);
Var
	total_sum,sum_oszlop : Integer;
BEGIN
	if k = n+1 then
		begin
			total_sum := 0;
			for i:=1 to n do
				begin
					sum_oszlop := 0;
					for j:=1 to m do
						begin
							if v[j] = 1 then
								sum_oszlop := sum_oszlop * a[i,j]
										else
								sum_oszlop := sum_oszlop - a[i,j];
						end;
					if -sum_oszlop > sum_oszlop then
						sum_oszlop := -1*sum_oszlop;
					total_sum := total_sum + sum_oszlop;
				end;
		if total_sum > MAX then
			MAX := total_sum
	end
		else
			for i:=0 to 1 do
				begin
					v[k]:=i;
					bkt(k+1);
				end;
END;

BEGIN

	Assign(f,'flip.in');
	Assign(g,'flip.out');
	Reset(f); Rewrite(g);
	
	MAX := -MaxInt; 
	
	Read(f,n,m);
	for i:=1 to n do
		for j:=1 to m do
			Read(f,a[i,j]);
			
	bkt(1);
	
	Write(g,MAX);
	
	Close(f); Close(g);

END.