Cumulative number of stars which have become Cepheids by the time, t, for the control simulations normalized to the number of ProCeps which is taken at the beginning. Cepheids originating from ProCeps (solid lines) are plotted separately from the ones originating from stars of m < m_min,Ceph (dotted lines). The metallicity of the models is indicated by colour. The thin vertical solid lines show the time t_He,end, namely, the time of the least massive non-interacting Cepheid which can occur at a given metallicity; all the Cepheids occurring later than t_He,end gained some of their mass in interaction with their companion.