#include <bits/stdc++.h>

using i64 = long long;

bool check(const std::vector<int>& a, int n, int k, double mid) {
    std::vector<double> adj(n);
    for (int i = 0; i < n; ++i) {
        adj[i] = a[i] - mid;
    }

    double sum = 0;
    int cnt = 0;
    for (int i = 0; i < n; ++i) {
        sum += adj[i];
        if (sum >= 0) {
            cnt++;
            sum = 0;
        }
    }

    return cnt >= k;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int n, k;
    std::cin >> n >> k;

    std::vector<int> a(n);
    for (int i = 0; i < n; ++i) {
        std::cin >> a[i];
    }

    double lo = 1.0, hi = 1000.0;
    while (hi - lo > 1e-9) {
        double mid = lo + (hi - lo) / 2;
        if (check(a, n, k, mid)) {
            lo = mid + 1e-9;
        } else {
            hi = mid - 1e-9;
        }
    }

    std::cout << std::fixed << std::setprecision(9) << lo;

    return 0;
}