Hey,I come here to explain my similiar solution in last div 2; Actually ,I was very amused when I saw the e_mail. Thus,I go to see the similiar solution and find it is really alike; However, an evidence can confirm my innocence. In the solution 12590491 by skyblue02,he used pair. And you can go to see all my submissions since I used codeforces,I never use pair; In face , the problem 1599C is a very easy problem ,and the solution is single. So i think it is just a concidence; thanks for your reading and hope you can reply me soon.