#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define int long long
#define PII pair<int, int>
const int mod = 1e9 + 7;
const int N = 2e5 + 5;
int n, k, a[N], pre[N], dp[N];
double tmp[N]; // dp[i]表示i节点出去到n的方案数
bool check(double x)
{
    fill(dp + 1, dp + 1 + n, -1e9);
    for (int i = 1; i <= n; i++)
        tmp[i] = a[i] - x, tmp[i] += tmp[i - 1];
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j < i; j++)
        {
            if (tmp[i] - tmp[j] >= 0)
                dp[i] = max(dp[i], dp[j] + 1);
        }
    }
    return dp[n] >= k;
}
void solve()
{
    cin >> n >> k;
    for (int i = 1; i <= n; i++)
        cin >> a[i], pre[i] = a[i] + pre[i - 1];
    double l = 0, r = pre[n] * 1.0 / n, ans = 0;
    for (int i = 1; i <= 200; i++)
    {
        double mid = (l + r) * 0.5;
        if (check(mid))
        {
            ans = mid;
            l = mid;
        }
        else
            r = mid;
    }
    cout << fixed << setprecision(10) << ans;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    // cin >> T;
    while (T--)
        solve();

    return 0;
}