Gas problem,needed before 9 pm plllllllls ?

A 2 litre flask contains ( n ) moles of N2 at 0.5 ATM at ( T )degree Kelvin , on addition of 0.01 moles of oxygen O2 its necessary to cool the flask to a temp. of 10 degree clesius in order to retain the same pressure , calculate the number of moles( n ) and the temp. ( T ) in kelvin