An unknown compound contains only carbon, hydrogen, nitrogen, and oxygen. Complete combustion of a 2.77 g sample of the compound gives 6.64 g CO2 and 1.67 g H2O. Another sample of mass 1.69 g was found to contain 0.143 g N. The molar mass of the compound was found to be 165 g mol−1. Find the molecular formula of the unknown compound.