#include <bits/stdc++.h>
#define st first
#define nd second
using lint = long long;
constexpr int mod = 998244353;
constexpr int inf = 0x3f3f3f3f;
constexpr lint linf = 0x3f3f3f3f3f3f3f3f;
using namespace std;

int main(){
    cin.tie(nullptr)->sync_with_stdio(false);
    int n, k;
    cin>>n>>k;
    vector<int>a(n);
    for(int i=0;i<n;i++) cin>>a[i];
    double lo = 0, hi = 1000;
    for(int z=0;z<60;z++){
        double mid = (lo + hi) / 2;
        vector<double>b(n);
        for(int i=0;i<n;i++) b[i] = a[i] - mid;
        map<double, int>dp;
        dp[0] = 0;
        double pref = 0;
        int ans = 0;
        for(int i=0;i<n;i++){
            pref += b[i];
            auto it = dp.lower_bound(pref);
            int cnt = 0;
            if(it == dp.begin()) continue;
            it--;
            cnt = it->nd + 1;
            if(it != dp.end() && next(it)->nd == cnt){
                dp.erase(next(it));
            }
            dp[pref] = cnt;
            if(i == n-1) ans = cnt;
        }
        if(ans >= k) lo = mid;
        else hi = mid;
    }
    cout<<fixed<<setprecision(6);
    cout<<lo<<"\n";
    return 0;
}