#include <bits/stdc++.h>
using namespace std;
const int max_n = 222222, inf = 1111111111;
int n, k;
long long sum0[max_n];
double ans, a[2][max_n], sum1[max_n], dp[2][max_n];
vector<pair<long long, double> > v;
double get(pair<long long, double> a, pair<long long, double> b) {
  return (b.second - a.second) / (a.first - b.first);
}
void add(long long k, double x) {
  while (v.size()) {
    pair<long long, double> p = v[v.size() - 1];
    if (p.first == k) {
      if (x > p.second) {
        v.pop_back();
      } else {
        break;
      }
    }
    pair<long long, double> p2 = v[v.size() - 2];
    double x1 = get(p, p2);
    double x2 = get(p, make_pair(k, x));
    if (x1 >= x2) {
      v.pop_back();
    } else {
      break;
    }
  }
  v.push_back(make_pair(k, x));
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 0; i < n; ++i) {
    int x;
    scanf("%d", &x);
    a[0][i] = sum0[i] = x;
    a[1][i] = sum1[i] = 1.0 / x;
    if (i) {
      sum0[i] += sum0[i - 1];
      sum1[i] += sum1[i - 1];
    }
    ans += 1.0 * sum0[i] / x;
  }
  int q1 = 0, q2 = 1;
  for (int i = 0; i < n; ++i) {
    dp[q1][i] = 0;
  }
  for (int i = 1; i < k; ++i) {
    v.clear();
    for (int j = 0; j < i; ++j) {
      add(sum0[j], dp[q1][j] - sum1[j] * sum0[j]);
    }
    int poz = 0;
    for (int j = i; j < n; ++j) {
      poz = min(poz, (int)v.size() - 1);
      while (poz + 1 < v.size()) {
        double x = get(v[poz], v[poz + 1]);
        if (sum1[j] > x) {
          ++poz;
        } else {
          break;
        }
      }
      dp[q2][j] = v[poz].first * sum1[j] + v[poz].second;
      add(sum0[j], dp[q1][j] - sum1[j] * sum0[j]);
    }
    swap(q1, q2);
  }
  printf("%.10f\n", ans - dp[q1][n - 1]);
  return 0;
}
