A sample of a liquid is kept at \( 1 \, \text{atm} \). It is compressed to \( 5 \, \text{atm} \) which leads to change of volume of \( 0.8 \, \text{cm}^3 \). If the bulk modulus of the liquid is \( 2 \, \text{GPa} \), the initial volume of the liquid was _______ litre. [Take \( 1 \, \text{atm} = 10^{5} \, \text{Pa} \)]