program flip;
var n, m, i, j, s, st:longint;
    f, g:text;
    a:array[1..16,1..16] of 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
        s:=0;
        for j:=1 to m do
          begin
            read(f,a[i,j]);
            s:=s+a[i,j];
            st:=st+a[i,j];
          end;
        if s<0 then
          begin
            for j:=1 to m do
              a[i,j]:=0-a[i,j];
            st:=st+2*(0-s);
          end;
      end;
    for j:=1 to m do
      begin
        s:=0;
        for i:=1 to n do
          begin
            s:=s+a[i,j];
          end;
        if s<0 then
          begin
            st:=st+2*(0-s);
          end;
      end;
    writeln(g,st);
    close(f);
    close(g);
  end.