program joculflip;
uses crt;
var f,g:text;
    a:array[1..16,1..16]of longint;
    n,m,l,k,i,j,o:byte;
    s,s2,smax:longint;
begin
     assign(f,'flip.in');
     reset(f);
     assign(g,'flip.out');
     rewrite(g);
     readln(f,n,m);
     for i:=1 to n do
         begin
              for j:=1 to m do
                  read(f,a[i,j]);
              readln(f);
         end;
     s:=0;
     smax:=0;
     o:=0;
     repeat
            o:=o+1;
           for i:=1 to n do
               a[o,i]:=a[o,i]*(-1);
           for i:=1 to m do
               begin
                    for j:=1 to n do
                       a[j,i]:=a[j,i]*(-1);
                    for k:=1 to n do
                        for l:=1 to m do
                            s:=s+a[k,l];
                    if s>smax then
                            smax:=s;
                     s:=0;
                    for j:=1 to n do
                       a[j,i]:=a[j,i]*(-1);
               end;
           for i:=1 to n do
            a[o,i]:=a[o,i]*(-1);
     until o=n;;
     end;
     writeln(g,smax);
     close(f);
     close(g);
end.