Come on, have a cup of tea

Dhudhnath has two vessels containing $720\text{ ml}$ and $405\text{ ml}$ of milk respectively.

Milk from these containers is poured into glasses of equal capacity to their brim, but the milk from the two different vessels ( $720\text{ ml}$ and $405\text{ ml}$ ) can not be poured together in a single glass. They have to be poured separately into glasses of equal capacity.

Find the minimum number of glasses that can be filled.