摘要：
When Kefa came to the restaurant and sat at a table, the waiter immediately brought him the menu. There were n dishes. Kefa knows that he needs exactl 阅读全文
摘要：
Kefa decided to celebrate his first big salary by going to the restaurant. He lives by an unusual park. The park is a rooted tree consisting of n vert 阅读全文
摘要：
Kefa wants to celebrate his first big salary by going to restaurant. However, he needs company. Kefa has n friends, each friend will agree to go to th 阅读全文