For Example i want to put discount on different type of product(not same categories) and a specifice product it's also a different type of category should be free..

other wise free product has price if customer want to bye single product at Point of sale

Example

Category A (product)                Category B (Product)            Category C (Product)

1(price)                          +                   1(price)                            1  Free

Else Free product sale alone it should price