Description: A permutation p of size n is an array such that every integer from 1 to n occurs exactly once in this array. Let's call a permutation an almost identity permutation iff there exist at least n - k indices i (1 ≤ i ≤ n) such that pi = i. Your task is to count the number of almost identity permutations for given numbers n and k. Input Format: The first line contains two integers n and k (4 ≤ n ≤ 1000, 1 ≤ k ≤ 4). Output Format: Print the number of almost identity permutations for given n and k. Note: None