Substitution

Specification
Write a program which stores 11 players in a football team The program should then display a player in a given position e.g. 1-11 When the Space key is pressed, the program should substitute one player in the list for another

Enter this code:

Extension
Change the program so that it asks the user which player (1-11) they want to display and then displays the name of that player

Extension (2)
Change the program so that it asks the user which player they want to substitute and also to enter the name of the new player

Extension (3)
Add input validation so that the code added in extensions 1 and 2 only allows the user to enter a valid player number (1-11)