Adobe | MTS | 16 November

You need to buy cupcakes as you visit from one shop to another.You can either buy a cupcake, sell a cupcake or do nothing. You will be visiting Y shops.And initially you have X cupcakes.At the end of the journey you should have Z cupcakes.Input is three numbers X, Y, Z.You need to output the maximum number of cupcakes that one can have in the journey.