var f : text;
    n, m, i, j : byte;
   mat : array[1..16,1..16] of longint;
    x : array[1..16] of longint;
    s, max : longint;
 
procedure rez;
var s1 : longint;
begin
    s := 0;
    for i := 1 to n do begin
          s1 := 0;
          for j := 1 to m do
         if s1 > 0 then s := s + s1
         else s := s - s1;
     end;
     if s > max then max := s;
end;
 
procedure back(k : integer);
begin
     if k = m+ 1 then begin
         rez;
         exit;
     end;
     x[k] := 1;
     back(k + 1);
     x[k] := -1;
     back(k + 1);

end;
 
 begin
     assign(f,'flip.in'); reset(f);
     readln(f,n,m);
     s := 0;
     for i := 1 to n do
         for j := 1 to m do
         read(f,mat[i,j]);
     close(f);
     back(1);
     assign(f,'flip.out'); rewrite(f);
     writeln(f,max);
    close(f);
 end.