usernames1 = ['john', 'jim', 'jane', 'jack']
usernames2 = []

while usernames:
    current_username = usernames1.pop()
    print(f"{current_username.title()} is logging in.")
    usernames2.append(current_username)

print("\n")
for user in usernames2:
    print(f"{user.title()} logged in.")