friend_list_maintenance

def is_valid_index(list, index):
    if 0 <= index < len(list):
        return True


friends = input().split(', ')
counter_blacklisted = 0
counter_error = 0
command = input().split()

while not command[0] == 'Report':
    action = command[0]
    if action == 'Blacklist':
        name = command[1]
        if name in friends:
            friends[friends.index(name)] = 'Blacklisted'
            counter_blacklisted += 1
            print(f'{name} was blacklisted.')
        else:
            print(f"{name} was not found.")
    elif action == 'Error':
        index = int(command[1])
        if is_valid_index(friends, index):
            if not friends[index] == 'Blacklisted' and not friends[index] == 'Lost':
                print(f'{friends[index]} was lost due to an error.')
                friends[index] = 'Lost'
                counter_error += 1
    elif action == 'Change':
        index = int(command[1])
        new_name = command[2]
        if is_valid_index(friends, index):
            print(f'{friends[index]} changed his username to {new_name}')
            friends[index] = new_name

    command = input().split()

print(f"Blacklisted names: {counter_blacklisted}")
print(f"Lost names: {counter_error}")
print(*friends)