请问有人有2021-2022 Math Counts HandBook第250道的解法吗？

那个好像是Coach才有的。谢谢！

Stacia has five pairs of gloves, each pair being a different color. She washed them all and now wants to match up the pairs. She randomly pairs each left glove with a right glove. If all five pairs do not match, she randomly pairs them all up again, and repeats until all five pairs do match. What is the expected number of times she will pair the gloves until all of them match？