Histograms to illustrate the homogenizing cuts applied to the target stars. Top left: distribution of the number of radial velocity data points, stars with 10 observations or less are excluded (the plot is truncated toward larger numbers; more than 50 stars have more than 70 RV data points). Top right: distribution of the stellar mass; stars as massive as 5 M_⊙ or more are excluded. The mass distributions of the stars more likely to be on the RGB and HB are shown in green and orange, respectively. Bottom left: distribution of stellar surface gravity; stars with log(ɡ) equal to or less than 1.5 are excluded. Bottom right: distribution of stellar luminosity; stars as luminous as 1000 L_⊙ or more are excluded.