#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
double exc[N] = {0}, sum[N] = {0}, rev[N] = {0};
double t[N];
double dp[N][55];
inline double y(int x, int p) { return dp[x][p] - exc[x] + sum[x] * rev[x]; }
inline double g(int j, int k, int p) {
  return (y(j, p) - y(k, p)) / (sum[j] - sum[k]);
}
inline double cal(int l, int i) {
  return exc[i] - exc[l] - (rev[i] - rev[l]) * sum[l];
}
int q[N], top, tail;
inline void add(int i, int k) {
  while (top < tail - 1 &&
         g(i, q[tail - 1], k) < g(q[tail - 1], q[tail - 2], k))
    tail--;
  q[tail++] = i;
}
inline int getmax(int i, int k) {
  while (top < tail - 1 && g(q[top + 1], q[top], k) < rev[i]) top++;
  return q[top];
}
int main() {
  int n, K;
  scanf("%d%d", &n, &K);
  for (int i = 1; i <= n; ++i) scanf("%lf", t + i);
  for (int i = 1; i <= n; ++i) {
    sum[i] = sum[i - 1] + t[i];
    rev[i] = rev[i - 1] + 1.0 / t[i];
    exc[i] = exc[i - 1] + sum[i] / t[i];
  }
  for (int i = 1; i <= n; ++i) dp[i][1] = exc[i];
  for (int k = 2; k <= K; ++k) {
    top = tail = 0;
    q[tail++] = 0;
    for (int i = 1; i <= n; ++i) add(i, k - 1);
    for (int i = 1; i <= n; ++i) {
      if (i >= k) {
        int l = getmax(i, k - 1);
        dp[i][k] = dp[l][k - 1] + cal(l, i);
      } else
        dp[i][k] = 1e50;
    }
  }
  printf("%.10f\n", dp[n][K]);
}
