2681：MM Programming Club

ACM is popular in HDU. Many girls want to learn more about programming skills in ACM. As one of assistances of Lcy, Yifenfei is now busy preparing a new club called “MM Programming Club”. Of Course, He will be the leader of the club, and teach these girls patiently. After the news posted around the campus, as many as N girls are determined to take part in the club. However, the numbers of members are limited; Yifenfei will only select K of them. It is quite a difficult problem. Here is a list of all information about N girls. Each of them has intelligence value and prettiness value. He also wants these K members such that the difference of intelligence between any two of them must not be greater than MAXK (If K = 1, the difference is zero). Now he wants to maximize the Sum of these K girls’ prettiness value.

Many test case, please process to end of file. Each test first contains three integers N(1 <= N <= 200), K(1 <= K <= N), MAXK(1 <= MAXK <= 500). Then N lines follow. Each line contains two integers S, T (1 <= S, T <= 500). S represents the intelligence value, and T represents the prettiness value.

If he can’t succeed in selecting K girls, print “-1”. Otherwise, Print the maximum the Sum of these K girls’ prettiness value.