Placing Cards

Sanggeun lays $n$ cards ($4 \le n \le 10$) side by side on the floor. Each card has a single integer from $1$ to $99$ written on it. He wants to choose $k$ ($2 \le k \le 4$) of the cards and line them up from left to right in the chosen order to form a single integer. How many different integers can he make?

For example, suppose there are 5 cards showing 1, 2, 3, 13, 21. If he picks 3 of them, then laying out 2, 1, 13 in that order gives 2113, and laying out 21, 1, 3 in that order also gives 2113. Because different choices can produce the same integer, you must count only the distinct integers.

Given the numbers written on the $n$ cards, write a program that finds how many different integers can be formed by choosing $k$ of them.

The first line contains the number of cards $n$, and the second line contains the number of cards to choose $k$. Each of the next $n$ lines contains the number written on one card.

Print the number of different integers Sanggeun can make on the first line.

When the four cards are $1, 2, 12, 1$ and $k = 2$, Sanggeun can make the 7 integers $11, 12, 21, 112, 121, 122, 212$.