program infoarena_flip;

type stiva=array[1..100]of -1..1;
var ams,ev:boolean;
  m,n,k,max,sol:int64;
  st:stiva;
  a:array[1..16,1..16] of int64;
  f:text;
  procedure citire;
  var  i,j:int64;
    begin
    assign(f,'flip.in');reset(f);
    read(f,n,m);
     for i:=1 to n do
     begin
       readln(f);
       for j:=1 to m do
        read(f,a[i,j]);
     end;
     close(f);

    end;
  procedure tipar;
var i,j,s:int64;
  b:array[1..16,1..16]of int64;
begin
for i:=1 to n do
for j:=1 to m do
  b[i,j]:=a[i,j];
for i:=1 to n do
  if st[i]=1 then for j:=1 to m do b[i,j]:=-b[i,j];
for i:=n+1 to n+m do
if st[i]=1 then for j:=1 to n do b[j,i-n]:=-b[j,i-n];
s:=0;
for i:=1 to n do
for j:=1 to m do
s:=s+b[i,j];
if s>max then max:=s;
end;

begin
   citire;
   max:=0;
  k:=1;st[k]:=-1;
  while (k>0) do
  begin
    repeat
      ams:=(st[k]<1);
      if ams then st[k]:=st[k]+1;
      ev:=true;
      until (not ams)or(ams and ev);
      if ams then if (k=(m+n)) then tipar
                                else begin k:=k+1;st[k]:=-1;end
            else k:=k-1;
  end;
  assign(f,'flip.out');rewrite(f);write(f,max);close(f);
end.