With the World Cup in Brazil approaching, fans of Panini stickers are competing to finish their album. to complete their album. We ask you to implement a thumbnail sharing program (server) in C. The application allows collectors to submit their duplicates and to search for users with missing thumbnails. At each connection, the user (client) sends to the server his login and two strings of characters. The first is a list of duplicate numbers and the second is a list of missing thumbnail numbers. The server program holds a list of duplicates that users have sent in, each item in the list being a duplicate. The server program holds a list of duplicates that users have sent in, each item in the list consists of two pieces of information: the thumbnail number and the user ID of the user who submitted the duplicate. When a message is received, the server first updates its list: it deletes all the entries in the list that correspond to the current client and adds the recently received numbers. It then launches a search in the list based on the user's missing thumbnails and sends him the identifiers of the users with the missing numbers as duplicates.