3. In the city of Gentle-city, there live 19 gentlemen, any two of whom are either friends or enemies. At some point, each gentleman asked each of his friends to send a hate card to each of his enemies (gentleman A asks gentleman B to send a card to all enemies of gentleman B). Each gentleman fulfilled all the requests, and he sent each of his enemies as many cards as he was asked to. What is the maximum number of cards that could have been sent?
Answer: 1538.

## Examples of answer recording:

 100
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