#include <bits/stdc++.h>
using namespace std;
const int MOD = 1000000007;
const int MAX = 200005;
int arr[MAX];
double pref[MAX];
double pref2[MAX];
double rec[MAX];
pair<double, double> first(pair<double, double> a, pair<double, double> b) {
  double x = ((double)(b.second - a.second)) / (a.first - b.first);
  double y = a.first * x + a.second;
  return make_pair(x, y);
}
struct cht {
  vector<double> pts;
  vector<pair<double, double> > taken;
  void addline(pair<double, double> i) {
    if (taken.size() <= 1) {
      if (!taken.empty()) {
        pts.push_back(first(i, taken.back()).first);
      }
      taken.push_back(i);
    } else {
      while (taken.size() >= 2) {
        pair<double, double> l1 = taken[taken.size() - 1];
        pair<double, double> l2 = taken[taken.size() - 2];
        if (first(i, l2) > first(l1, l2)) {
          break;
        } else {
          taken.pop_back();
          pts.pop_back();
        }
      }
      pts.push_back(first(i, taken.back()).first);
      taken.push_back(i);
    }
  }
  double query(double x) {
    int idx = lower_bound(pts.begin(), pts.end(), x) - pts.begin();
    return taken[idx].first * x + taken[idx].second;
  }
  void gg() {
    for (auto i : taken) {
      cout << i.first << " " << i.second << endl;
    }
  }
};
double hrs(int l, int r) {
  return (pref2[r] - pref2[l - 1] - (rec[r] - rec[l - 1]) * pref[l - 1]);
}
double dp[MAX][55];
int main() {
  int n, k;
  cin >> n >> k;
  for (int i = 0; i < n; i++) {
    cin >> arr[i + 1];
  }
  for (int i = 1; i < n + 1; i++) {
    pref[i] = pref[i - 1] + arr[i];
  }
  for (int i = 1; i < n + 1; i++) {
    pref2[i] = pref2[i - 1] + pref[i] / arr[i];
  }
  for (int i = 1; i < n + 1; i++) {
    rec[i] = rec[i - 1] + 1.0 / arr[i];
  }
  for (int i = 1; i < n + 1; i++) {
    dp[i][1] = hrs(1, i);
  }
  for (int j = 2; j < k + 1; j++) {
    cht x;
    for (int i = j - 1; i < n + 1; i++) {
      if (i == j - 1) {
        dp[i][j] = 0;
      } else {
        dp[i][j] = pref2[i] + x.query(rec[i]);
      }
      x.addline({-pref[i], dp[i][j - 1] + rec[i] * pref[i] - pref2[i]});
    }
  }
  cout << fixed << setprecision(10) << dp[n][k] << endl;
}
