Thanks man for this solution I learnt alot from it.

Sorry guys, I'm fairly new to JScript, but I cannot get why it gives me "submission timed out" even with one test case, the one with the empty string. Tried locally and the solution works fine (even if probably not the most clever one, but still).

Thanks man.

Any hint of which bug you were talking about guys? Same problem here :(

Wrong, because: the first customer arrives with one 25£ note. He pays and on the till(that is supposed to be empty) now there is one 25£ note. The second arrives and he pretend to pay with one 50£ note, no problem the price of the ticket is 25£ and on the till there is one(1) 25£ note of change that the cashier can give him back. Now on the till there is one 50£ note and the cashier is already panicking because he knows that if the next customer arrives with a note that is not a 25£ one he can't give him/her the change back. The third customer finally arrives. With a shining 50£ note. Vasya, knowing his lack of change fakes a smile to the third customer, politely explaining him that there is no seats left in the theater because they have been already booked online. End.