[C/H] as a function of the effective temperature (on the left) and the surface gravity (on the right) for all the stars in our sample (top). A clear separation can be seen between the mixed and unmixed stars, with the exception of the four encircled stars. [N/H] with respect to T_eff and log ɡ are shown in the middle panels. The lower panel shows [O/H] as a function of T_eff and log ɡ. The yellow dashed line indicates the T_eff and log ɡ at the RGB bump. Symbols are the same as in Fig.7. Using H instead of Fe makes our unmixed stars are spreader, however it does not vanish the separation between mixed and unmixed.