program matrice;
var     v:array[1..16,1..16]of longint;
        n,m,i,j,k:integer;
        max,s,sn,sp:longint;
        f,g:text;
begin
assign(f,'flip.in');assign(g,'flip.out');
reset(f); rewrite(g);
readln(f,n,m);
max:=0;
for i:=1 to n do
begin
 for j:=1 to m do
 begin
  read(f,v[i,j]);
  max:=max+v[i,j];
 end;
 readln(f);
end;
s:=0;
for i:=1 to n do
begin
sn:=0; sp:=0;
 for j:=1 to m do
 begin
  if v[i,j]<0 then
   sn:=sn+v[i,j]
  else
   sp:=sp+v[i,j];
 end;
  for k:=1 to m do
   if (0-sn)>sp then
    begin
     v[i,k]:=0-v[i,k];
     s:=s+v[i,k];
    end
    else
     s:=s+v[i,k];
end;
if s>max then
 max:=s;
s:=0;
for j:=1 to m do
begin
 sn:=0; sp:=0;
 for i:=1 to n do
 begin
  if v[i,j]<0 then
   sn:=sn+v[i,j]
  else
   sp:=sp+v[i,j];
 end;
  for k:=1 to n do
   if (0-sn)>sp then
    begin
     v[k,j]:=0-v[k,j];
     s:=s+v[k,j];
    end
    else
     s:=s+v[k,j];
end;
if s>max then
 max:=s;
write(g,max);
close(f); close(g);
end.