World Conquest

Sejun has conquered N countries. He noticed that people from different countries are not close to one another, so he wants to form groups to help everyone become friendlier.

The groups must follow these rules.

• Each group must contain exactly K people.
• The people in one group must all come from different countries.

Given the number of people living in each country, find the maximum number of groups that can be formed. People who are not assigned to any group may be ignored.

For instance, if there are 5 countries with 4 people in each country and K is 4, at most 5 groups can be made. Each group can choose one person from 4 different countries among the 5 countries.

The first line contains the number of countries N and the group size K. Both are positive integers, and they satisfy K <= N <= 50 and K <= 20.

The second line contains N integers separated by spaces, where each integer is the number of people living in one country. Each number is between 1 and 1,000,000,000, inclusive.

Print the maximum number of groups that can be formed.

The answer is at most 2^63 - 1.