const r=16;c=16;
type tabel=array[1..r,1..c] of integer;
var t:tabel;
    i,j,s,m,n,max:integer;
    fi,fo:text;
procedure cr(r,nr:integer);
var i:integer;
begin
  for i:=1 to nr do t[r,i]:=(-1)*t[r,i];
end;
procedure cc(c,nc:integer);
var i:integer;
begin
  for i:=1 to nc do t[i,c]:=(-1)*t[i,c];
end;
function cs(t1:tabel;m,n:integer):integer;
var i,j,s:integer;
begin
s:=0;
  for i:=1 to m do
      for j:=1 to n do s:=s+t[i,j];
      cs:=s;
end;
begin
  assign(fi,'flip.in');
  reset(fi);
  assign(fo,'flip.out');
  rewrite(fo);
  readln(fi,m,n);
  for i:=1 to m do begin
     for j:=1 to n do read(fi,t[i,j]);
                   readln(fi);
                   end;
  max:=cs(t,m,n);
  for i:=1 to m do begin
                   cr(i,n);
     for j:=1 to n do begin
                        cc(j,m);
                        if cs(t,m,n)>max then max:=cs(t,m,n);
                        cc(j,m);
                      end;
                   cr(i,n);
                   end;
  if cs(t,m,n)>max then max:=cs(t,m,n);
  writeln(fo,max);
  close(fi);
  close(fo);
end.