Calling two different reports (jrxmls) based on the input parameter condition in jasper

Question

If i create two reports say A and B and now i need to call A or B depending on Parameter P1 value.

If P1 = 'X' then A is called and this report run and if P1 ='Y' then B is called.

How do we design this in Jasper (iReport/Server)?

Please advise.