#P1730F. Almost Sorted

    ID: 805 Type: RemoteJudge 2000ms 256MiB Tried: 0 Accepted: 0 Difficulty: 10 Uploaded By: Tags>bitmasksdata structuresdp*2700

Almost Sorted

Description

You are given a permutation pp of length nn and a positive integer kk. Consider a permutation qq of length nn such that for any integers ii and jj, where 1i<jn1 \le i < j \le n, we have pqipqj+k.p_{q_i} \le p_{q_j} + k.

Find the minimum possible number of inversions in a permutation qq.

A permutation is an array consisting of nn distinct integers from 11 to nn in arbitrary order. For example, [2,3,1,5,4][2,3,1,5,4] is a permutation, but [1,2,2][1,2,2] is not a permutation (22 appears twice in the array) and [1,3,4][1,3,4] is also not a permutation (n=3n=3 but there is 44 in the array).

An inversion in a permutation aa is a pair of indices ii and jj (1i,jn1 \le i, j \le n) such that i<ji < j, but ai>aja_i > a_j.

The first line contains two integers nn and kk (1n50001 \le n \le 5000, 1k81 \le k \le 8).

The second line contains nn distinct integers p1,p2,,pnp_1, p_2, \ldots, p_n (1pin1 \le p_i \le n).

Print the minimum possible number of inversions in the permutation qq.

Input

The first line contains two integers nn and kk (1n50001 \le n \le 5000, 1k81 \le k \le 8).

The second line contains nn distinct integers p1,p2,,pnp_1, p_2, \ldots, p_n (1pin1 \le p_i \le n).

Output

Print the minimum possible number of inversions in the permutation qq.

Sample Input 1

1 1
1

Sample Output 1

0

Sample Input 2

3 1
2 3 1

Sample Output 2

1

Sample Input 3

5 2
5 4 3 2 1

Sample Output 3

6

Sample Input 4

10 3
5 8 6 10 2 7 4 1 9 3

Sample Output 4

18

Note

In the first example, the only permutation is q=[1]q = [1] (00 inversions). Then pq1=1p_{q_1} = 1.

In the second example, the only permutation with 11 inversion is q=[1,3,2]q = [1, 3, 2]. Then pq1=2p_{q_1} = 2, pq2=1p_{q_2} = 1, pq3=3p_{q_3} = 3.

In the third example, one of the possible permutations with 66 inversions is q=[3,4,5,1,2]q = [3, 4, 5, 1, 2]. Then pq1=3p_{q_1} = 3, pq2=2p_{q_2} = 2, pq3=1p_{q_3} = 1, pq4=5p_{q_4} = 5, pq5=4p_{q_5} = 4.