In a party, there are 10 pairs arriving, each consisting of a boy and a girl. Then, there is a dance, where each boy dances with one girl (and one girl only). Each boy is equally likely to dance with each girl, and each girl is equally likely to dance with each boy. Naturally, it is likely that there are some boy-girl pairs who dance together, and who arrived together too. A squad is defined as a collection of boy-girl pairs, where boys and girls are dancing within the squad. No member in a squad can be dancing with anyone not part of that squad. Note that if a boy-girl pair is dancing together, that one single pair is also a squad on its own. Naturally, multiple such squads can form among the 10 pairs who came to the party. What is the expected number of squads