var f:text;
    i,j,k,n,m:byte;
    s1,s2:longint;
    a:array [1..16,1..16] of longint;
    s,s3:array [1..16] of longint;
begin
  assign (f,'flip.in');
  reset (f);
  readln (f,n,m);
  s1:=0;s2:=0;
  for i:=1 to n do
  for j:=1 to m do
  begin
    read (f,a[i,j]);
    s1:=s1+a[i,j];
    s2:=s2+(-1*a[i,j]);
    s[j]:=s[j]+a[i,j];
    s3[j]:=s3[j]+(-1*a[i,j]);
    if j=m then
    begin
      if s1<s2 then
      for k:=m downto 1 do
      begin
        a[i,k]:=a[i,k]*(-1);
        s[j]:=s[j]+(2*a[i,k])
      end;
      s1:=0;s2:=0
    end;
    if (i=n) and (s[j]<s3[j]) then
    for K:=n downto 1 do
    a[k,j]:=a[k,j]*(-1);
  end;
  s1:=0;
  close (f);
  assign (f,'flip.out');rewrite (f);
  for i:=1 to n do
  for j:=1 to m do
  s1:=s1+a[i,j];
  writeln (f,s1);
  close (f);
end.