#include <bits/stdc++.h>
using namespace std;
long long rdtsc() {
  long long tmp;
  asm("rdtsc" : "=A"(tmp));
  return tmp;
}
inline int myrand() { return rand(); }
inline int rnd(int x) { return myrand() % x; }
void precalc() {}
const long double eps = 1e-9;
const long double inf = 1e18;
const int maxn = 2e5 + 10;
const int maxk = 55;
int n, k;
int t[maxn];
bool read() {
  if (scanf("%d%d", &n, &k) < 2) {
    return false;
  }
  for (int i = 0; i < n; ++i) {
    scanf("%d", &t[i]);
  }
  return true;
}
long double pinv[maxn];
long long p[maxn];
long double pp[maxn];
long double dp[maxk][maxn];
int g[maxn];
void calcdp(int it, int l, int r) {
  if (r - l == 1) {
    return;
  }
  int mid = (l + r) / 2;
  int cg = -1;
  long double val = inf;
  for (int i = min(mid - 1, g[l]); i <= min(mid - 1, g[r]); ++i) {
    long double cval =
        dp[it][i] + pp[mid] - pp[i] - p[i] * (pinv[mid] - pinv[i]);
    if (cval < val + eps) {
      val = cval;
      cg = i;
    }
  }
  assert(cg != -1);
  g[mid] = cg;
  dp[it + 1][mid] = val;
  calcdp(it, l, mid);
  calcdp(it, mid, r);
}
void solve() {
  p[0] = 0;
  pinv[0] = 0.0L;
  pp[0] = 0.0L;
  for (int i = 0; i < n; ++i) {
    p[i + 1] = p[i] + t[i];
    pinv[i + 1] = pinv[i] + (long double)1 / t[i];
    pp[i + 1] = pp[i] + (long double)p[i + 1] / t[i];
  }
  for (int it = 0; it <= k; ++it) {
    for (int i = 0; i <= n; ++i) {
      dp[it][i] = inf;
    }
  }
  dp[0][0] = 0;
  for (int it = 0; it < k; ++it) {
    g[0] = 0, g[n + 1] = n;
    calcdp(it, it, n + 1);
  }
  printf("%.18f\n", (double)dp[k][n]);
}
int main() {
  srand(rdtsc());
  precalc();
  while (true) {
    if (!read()) {
      break;
    }
    solve();
  }
  return 0;
}
