Upper panels: difference between the median of the 2P and 1P abundance of each analyzed element. Positive and negative values (above and below the green line), represent enrichment and depletion of 2P stars, respectively. The right panel displays the 2P–1P helium difference (in mass fraction) from Milone et al. (2018). Lower panels: diagrams of Δ[N/Fe] vs. Δ[C/Fe] (left), Δ[Na/Fe] vs. Δ[O/Fe] (middle), and Δ[Al/Fe] vs. Δ[Mg/Fe] (right). Each point is color coded according to their [Fe/H], following the scheme represented in the color bar. Smaller dots indicate Δ[C/Fe] and Δ[N/Fe] based on RGB stars above the bump.