#include <bits/stdc++.h>
using namespace std;
const int N = 200005;
int n, K, a[N], q[N];
double s1[N], s2[N], s3[N], dp[51][N];
inline int read() {
  int a = 0, f = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    a = a * 10 + c - '0';
    c = getchar();
  }
  return a * f;
}
inline double calc(int k, int l, int r) {
  return dp[k][l] + s3[r] - s3[l] - (s2[r] - s2[l]) * s1[l];
}
inline double slop(int k, int l, int r) {
  return (double)((dp[k][l] - s3[l] + s2[l] * s1[l]) -
                  (dp[k][r] - s3[r] + s2[r] * s1[r])) /
         (s1[l] - s1[r]);
}
int main() {
  n = read();
  K = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  for (int i = 1; i <= n; i++) s1[i] = s1[i - 1] + a[i];
  for (int i = 1; i <= n; i++) s2[i] = s2[i - 1] + (double)1.0 / a[i];
  for (int i = 1; i <= n; i++) s3[i] = s3[i - 1] + (double)s1[i] / a[i];
  for (int i = 1; i <= n; i++) dp[1][i] = s3[i];
  for (int j = 2; j <= K; j++) {
    int t = 1, w = 1;
    q[1] = j - 1;
    for (int i = j; i <= n; i++) {
      while (t < w && calc(j - 1, q[t], i) >= calc(j - 1, q[t + 1], i)) t++;
      dp[j][i] = calc(j - 1, q[t], i);
      while (t < w && slop(j - 1, q[w - 1], q[w]) >= slop(j - 1, q[w], i)) w--;
      q[++w] = i;
    }
  }
  printf("%.10lf\n", dp[K][n]);
  return 0;
}
