#include <iostream>

#include <algorithm>

#include <map>

#include <vector>

#include <set>

#include <math.h>

#include <queue>

#include <assert.h>

#include <stdio.h>

#include <stdlib.h>

using namespace std;

typedef long long ll;

#define INF 2147483647

//输入

int n, k;

double a[];    

//返回分成k段最大的段长

double solve(ll sum) {

    ll l = , r = sum+;    //二分的左右端

    ll mx = ;        //保存结果

    while (l < r) {

        ll mid = (l + r) / ;

        ll sum = ;        //段数求和

        for (int i = ; i < n; i++) sum += a[i] / mid;    

        //每段长mid，可以分成k段

        if (sum >= k) {

            mx = max(mx, mid);    //更新答案

            l = mid + ;

        }

        else {

            r = mid;

        }

    }

    return 1.0*mx/;

}

int main() {

    cin >> n >> k;

    ll sum = ;

    for (int i = ; i < n; i++) {

        cin >> a[i];

        a[i] *= ;    //将段长乘以100

        sum += a[i];    //对段长求和

    }

    printf("%.2lf",solve(sum));

    getchar(); getchar();

    return ;

}