class File:

    def __init__(self):
        self.file = []

    def est_vide(self):
        if self.file is None:
            return True

    def enfile(self, x):
            return self.file.append(x)

    def defile(self):
        if self.est_vide():
            return False
        else:
            return self.file.pop(0)

    def affiche(self):
        for i, elem  in enumerate(reversed(self.file)):
            if i == len(self.file)-1:
                print(elem, end="")
            else:
                print(f"{elem} ->"  ,end="")
        print()

    def dernier_file(self, n):













f = File()
for x in [0, 1, 2, 3, 4]:
    f.enfile(x)
f.defile()
f.enfile(f.defile())
f.enfile(f.defile())
f.affiche()