A 2.52 g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen and sulfur was burned in excess O to yield 4.23 g of CO2 and 1.01 g H2O. Another sample of the same compound, of mass 4.14 g, yielded 2.11 g SO3. A third sample, of mass 5.66 g, yielded 2.27 g HNO3. Calculate the empirical formula of the compound.