Team Name

Сhef has assembled a football team! Now he needs to choose a name for his team. There are $N$ words in English that Chef considers *funny*. These words are $s_1, s_2, \dots, s_N$. Chef thinks that a good team name should consist of two words such that they are not funny, but if we swap the first letters in them, the resulting words are funny. Note that under the given constraints, this means th