var i,j,max,n,m,s:integer;
    st:array[1..100] of integer;
    f,g:text;
    a:array[1..16,1..16] of integer;

procedure back;
var k:longint;
begin
k:=1;
max:=-maxint;
st[k]:=0;
while k>0 do
      begin
      if st[k]<2 then
      begin
      inc(st[k]);
      s:=0;
      if k=m+n then
         begin
         for i:=1 to m do
	 for j:=1 to n do
             begin
             if (st[i]=1) and (st[m+j]<>1) then s:=s-a[i,j]
		else
		s:=s+a[i,j];
             end;
          if s>max then max:=s
          end
         else
         begin
              k:=k+1;
              st[k]:=0;
         end;
         end else
      k:=k-1;
      end;
end;

begin
assign(f,'flip.in');
reset(f);
assign(g,'flip.out');
rewrite(g);
read(f,m,n);
for i:=1 to m do
for j:=1 to n do read(a[i,j]);
back;
write(g,max);
close(f);
close(g);
end.