#include <bits/stdc++.h>
using namespace std;
template <class T>
inline T bigmod(T p, T e, T M) {
  T ret = 1;
  for (; e > 0; e >>= 1) {
    if (e & 1) ret = (ret * p) % M;
    p = (p * p) % M;
  }
  return (T)ret;
}
template <class T>
inline T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
template <class T>
inline T lcm(T a, T b) {
  a = abs(a);
  b = abs(b);
  return (a / gcd(a, b)) * b;
}
template <class T, class X>
inline bool getbit(T a, X i) {
  T t = 1;
  return ((a & (t << i)) > 0);
}
template <class T, class X>
inline T setbit(T a, X i) {
  T t = 1;
  return (a | (t << i));
}
template <class T, class X>
inline T resetbit(T a, X i) {
  T t = 1;
  return (a & (~(t << i)));
}
inline long long power(long long a, long long b) {
  long long multiply = 1;
  for (int i = (1); i <= (b); i++) {
    multiply *= a;
  }
  return multiply;
}
inline long long ABS(long long a) { return (a >= 0) ? a : -a; }
int n, k;
double t[200001], cum[200001];
double divcum[200001], invcum[200001];
double dp[200001][51];
inline double calc(int a, int b) {
  return divcum[b] - divcum[a - 1] - (cum[a - 1] * (invcum[b] - invcum[a - 1]));
}
inline void cnt(int j, int l, int r, int optl, int optr) {
  if (l > r) return;
  if (l == r) {
    dp[l][j] = (1LL << 62) - 1;
    for (int i = (optl); i <= (optr); i++)
      dp[l][j] = min(dp[l][j], dp[i - 1][j - 1] + calc(i, l));
  }
  int mid = (l + r) / 2, m;
  double optm = (1LL << 62) - 1;
  for (int i = (optl); i <= (optr); i++) {
    if (dp[i - 1][j - 1] + calc(i, mid) < optm) {
      optm = dp[i - 1][j - 1] + calc(i, mid);
      m = i;
    }
  }
  dp[mid][j] = optm;
  cnt(j, l, mid - 1, optl, m);
  cnt(j, mid + 1, r, m, optr);
}
int main() {
  cin >> n >> k;
  cum[0] = 0;
  divcum[0] = 0;
  invcum[0] = 0;
  for (int i = (1); i <= (n); i++) {
    cin >> t[i];
    cum[i] = cum[i - 1] + t[i];
    divcum[i] = divcum[i - 1] + (double)(cum[i] / (t[i] * 1.0));
    invcum[i] = invcum[i - 1] + 1.0 / t[i];
  }
  for (int i = (1); i <= (n); i++) {
    dp[i][1] = calc(1, i);
  }
  for (int j = (2); j <= (k); j++) {
    cnt(j, j, n, j, n);
  }
  cout << setprecision(7) << fixed << dp[n][k] << '\n';
  return 0;
}
