Professor Frankstein and his wife were invited to a ball in Newtonia to celebrate the discovery of a new metal. When they arrived there, they found six other couples. In Newtonia, there was a custom according to which people meeting each other for the first time exchanged a flower.
After all the people finished exchanging flowers, Prof. Frankstein decided to find out how many flowers each person had received and started interrogating everyone, his wife included. He got thirteen distinct replies. How many flowers did Mrs. Frankstein receive?