#include <bits/stdc++.h>
using namespace std;
const long long N = 35;
const long long M = 205;
long long n, k;
long long a[N], idx[N];
double ans = 0;
bool vis[N][N][M];
double cache[N][N][M];
long long newidx(long long i, long long l, long long r) {
  if (i < l || i > r) return i;
  long long gap = (i - l);
  long long idx = (r - gap);
  return idx;
}
double dp(long long idx1, long long idx2, long long k) {
  if (k == 0) return (idx1 > idx2);
  if (vis[idx1][idx2][k]) return cache[idx1][idx2][k];
  vis[idx1][idx2][k] = 1;
  double &ans = cache[idx1][idx2][k];
  ans = 0;
  for (long long i = 1; i <= n; i++) {
    for (long long j = i; j <= n; j++) {
      long long newi = newidx(idx1, i, j);
      long long newj = newidx(idx2, i, j);
      ans += dp(newi, newj, k - 1);
    }
  }
  ans /= (n * (n + 1) / 2);
  return ans;
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n >> k;
  for (long long i = 1; i <= n; i++) {
    cin >> a[i];
    idx[a[i]] = i;
  }
  for (long long i = 1; i <= n; i++)
    for (long long j = i + 1; j <= n; j++) ans += dp(idx[i], idx[j], k);
  cout << fixed << setprecision(12) << ans;
  return 0;
}
