What is the cost from the station “issy Val de seine” (RER C) to “marne la vallee chessy”(RER A). I have to change 3 RER (RERC-RERB-RERA). What kind of ticket shall I buy from the station “issy val de seine “? Does it cost 5€ or is it more expensive because of changing 3 RER?
A regular RER ticket purchased at Issy Val-de-Seine to Marne la Vallée, for 5€ would cover your entire trip on the RER C, RER B, RER A. See this itinerary.
You don't have to do anything special to buy this RER ticket when you're at Issy Val-de-Seine station. If you buy from the ticket window, simply ask for "Marne la Vallée" or "Disneyland". The agent will print you a ticket covering the entire route.
At automated ticket machines you'll specify: 1) starting from this station (Issy Val de Seine), 2) destination: Marne la Vallée, and the machine will print you out a custom ticket for this voyage.
Because of the RER ticket price ceiling changes a couple years back, the price of this RER ticket is 5€. Previous to this change, it would have been more expensive, but not today.