#include <bits/stdc++.h>
using namespace std;
int x[10], p[50], dp[200][200];
int pp[50], q[50];
int n, k;
int maxi;
double suma;
int nm = 0;
void check(int a, int b, int c, int d) {
  nm++;
  for (int i = 1; i <= n; i++) p[i] = x[i];
  int br = q[a];
  for (int j = pp[a]; j <= ((q[a] + pp[a]) >> 1); j++) {
    int pom = p[j];
    p[j] = p[br];
    p[br] = pom;
    br--;
  }
  if (b > 0) {
    int br = q[b];
    for (int j = pp[b]; j <= ((q[b] + pp[b]) >> 1); j++) {
      int pom = p[j];
      p[j] = p[br];
      p[br] = pom;
      br--;
    }
  }
  if (c > 0) {
    int br = q[c];
    for (int j = pp[c]; j <= ((q[c] + pp[c]) >> 1); j++) {
      int pom = p[j];
      p[j] = p[br];
      p[br] = pom;
      br--;
    }
  }
  if (d > 0) {
    int br = q[d];
    for (int j = pp[d]; j <= ((q[d] + pp[d]) >> 1); j++) {
      int pom = p[j];
      p[j] = p[br];
      p[br] = pom;
      br--;
    }
  }
  int cnt = 0;
  for (int j = 1; j <= n; j++)
    for (int f = (j + 1); f <= n; f++)
      if (p[j] > p[f]) cnt++;
  suma = suma + cnt;
}
int main() {
  srand(0);
  scanf("%d%d", &n, &k);
  suma = 0.0;
  maxi = n * (n + 1) / 2;
  int pom = maxi;
  for (int i = 2; i <= 4; i++) {
    if (k < i) break;
    pom = pom * maxi;
  }
  maxi = pom;
  for (int i = 1; i <= n; i++) scanf("%d", &x[i]);
  int cnt = 0;
  for (int i = 1; i <= n; i++)
    for (int j = i; j <= n; j++)
      if (x[i] > x[j]) cnt++;
  int i, j, i1, i2, j1, j2;
  int br = 0;
  for (i = 1; i <= n; i++)
    for (j = i; j <= n; j++) {
      pp[++br] = i;
      q[br] = j;
    }
  int ppp = 0;
  for (i = 1; i <= br; i++) {
    if (k == 1) {
      check(i, 0, 0, 0);
      continue;
    }
    for (j = 1; j <= br; j++) {
      if (k == 2) {
        check(i, j, 0, 0);
        continue;
      }
      for (i1 = 1; i1 <= br; i1++) {
        if (k == 3) {
          check(i, j, i1, 0);
          continue;
        }
        for (i2 = 1; i2 <= br; i2++) {
          check(i, j, i1, i2);
          ppp++;
        }
      }
    }
  }
  suma = suma / maxi;
  printf("%.11lf\n", suma);
}
