2.5 g of protein containing only glycine (C₂H₅NO₂) is dissolved in water to make 500 mL of solution. The osmotic pressure of this solution at 300 K is found to be $5.03\times {10}^{-3}\text{ bar }$. The total number of glycine units present in the protein is __________.
(Given : R = 0.083 L bar K^-1 mol^-1)