var f,g:text;
        a:array[1..16,1..16] of longint;
        s,s1,smax:longint;
        k,i,j,n,m:byte;
        x:array[0..16] of byte;
    begin
         assign(f,'flip.in'); reset(f);
        assign(g,'flip.out'); rewrite(g);
        read (f,n,m);
        for i:=1 to n do begin
            for j:=1 to m do
                read (f,a[i,j]);
                readln(f);
        end;
        k:=1;
        for i:=1 to n do x[i]:=0;
            while k>0 do begin
                  if x[k]<2 then x[k]:=x[k]+1;
                  if k=n then
                  begin
                     s1:=0;
                     for j:=1 to m do begin
                     s:=0;
                     for i:=1 to n do begin
                         if x[i]=2 then s:=s-a[i,j] else
                            s:=s+a[i,j];
                  end;
        if s<0 then s1:=s1-s else
        s1:=s1+s;
      end;
       if s1>smax then smax:=s1;
       while x[k]=2 do begin k:=k-1; end;
      end else begin k:=k+1; x[k]:=0; end;
     end;
     write(g,smax);
     close(f);
     close(g);
   end.