#include <bits/stdc++.h>

using namespace std;

const int N = 2e5 + 5;

int n, a[N];
double f[N];
int val[N], g[N], mx[N];

void modify(int x, int y) {
    for (; x <= n; x += x & -x) mx[x] = max(mx[x], y);
}

int query(int x) {
    int res = 0;
    for (; x; x -= x & -x) res = max(res, mx[x]);
    return res;
}

signed main() {
    int m; scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; ++i) scanf("%d", &a[i]);
    double L = 1, R = 1000;
    while (fabs(L - R) > 1e-6) {
        double mid = (L + R) / 2;
        vector< pair<double, int> > tp;
        for (int i = 1; i <= n; ++i) {
            f[i] = f[i - 1] + a[i] - mid;
            tp.push_back(make_pair(f[i], i));
            mx[i] = 0;
        }
        sort(tp.begin(), tp.end());
        int cnt = 0;
        for (auto [x, y] : tp) {
            g[y] = 0, val[y] = ++cnt;
        }
        for (int i = 1; i <= n; ++i) if (f[i] > 0) {
            g[i] = query(val[i]);
            modify(val[i], g[i] + 1);
        }
        if (*max_element(g + 1, g + n + 1) >= m) {
            L = mid;
        } else {
            R = mid;
        }
    }
    printf("%.6lf\n", L);
    return 0;
}