A first study of CP violation in the decay modes and , where h labels a K or 蟺 meson and D labels a D0 or meson, is performed. The analysis uses the LHCb data set collected in pp collisions, corresponding to an integrated luminosity of 3 fb−1. The analysis is sensitive to the CP-violating CKM phase 纬 through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of 纬 using other decay modes.