#include <bits/stdc++.h>
using namespace std;
const int MAXN = 105;
double prob1[MAXN][MAXN], prob2[MAXN][MAXN], part1[MAXN][MAXN],
    part2[MAXN][MAXN];
int perm[MAXN], n, k;
double part3[MAXN][MAXN], part4[MAXN][MAXN], part5[MAXN][MAXN],
    part6[MAXN][MAXN];
void compute() {
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < n; ++j) prob2[i][j] = 0;
  for (int i = 0; i < n; ++i)
    for (int j = 1; j <= i; ++j) {
      part1[j][i] = part1[j - 1][i] + prob1[j - 1][i];
      part2[j][i] = part2[j - 1][i] + part1[j][i];
    }
  for (int i = 0; i < n; ++i)
    for (int j = 1; j <= n - i - 1; ++j) {
      part3[i][j] = part3[i][j - 1] + prob1[i][i + j];
      part4[i][j] = part4[i][j - 1] + part3[i][j];
    }
  for (int i = 1; i < n; ++i)
    for (int j = 1; j <= n - i; ++j) {
      part5[i][j] = part5[i][j - 1] + prob1[j - 1][j - 1 + i];
      part6[i][j] = part6[i][j - 1] + part5[i][j];
    }
  for (int i = 0; i < n; ++i)
    for (int j = i + 1; j < n; ++j) {
      prob2[i][j] = (i * (i + 1) / 2 + (n - j - 1) * (n - j) / 2 +
                     (j - i) * (j - i - 1) / 2) *
                    prob1[i][j];
      prob2[i][j] += part2[j][j] - part2[j - i - 1][j] - part2[i][j];
      prob2[i][j] +=
          part4[i][n - i - 1] - part4[i][n - j - 1] - part4[i][j - i - 1];
      prob2[i][j] +=
          (i + 1) * (n - j) -
          (part6[j - i][i + n - j] - part6[j - i][n - j - 1] - part6[j - i][i]);
      prob2[i][j] /= (n * (n + 1) / 2);
    }
  for (int i = 0; i < n; ++i)
    for (int j = i + 1; j < n; ++j) prob1[i][j] = prob2[i][j];
}
int main() {
  cin >> n >> k;
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < n; ++j) {
      part1[i][j] = part2[i][j] = part3[i][j] = part4[i][j] = part5[i][j] =
          part6[i][j] = 0;
    }
  for (int i = 0; i < n; ++i) cin >> perm[i];
  for (int i = 0; i < n; ++i)
    for (int j = i + 1; j < n; ++j) {
      prob1[i][j] = (perm[i] > perm[j]);
    }
  for (int i = 0; i < min(k, 2005); ++i) compute();
  double sum = 0;
  for (int i = 0; i < n; ++i)
    for (int j = i + 1; j < n; ++j) sum += prob1[i][j];
  cout << fixed << setprecision(9) << sum << endl;
}
