/*
 * @Author: your name
 * @Date: 2020-10-20 07:19:01
 * @LastEditTime: 2021-04-16 18:52:41
 * @LastEditors: Please set LastEditors
 * @Description: In User Settings Edit
 * @FilePath: \vscodecpp\OJ.cpp
 */
#include <iostream>
#include<cstdio>
using namespace std;
const int N=1e5+10;
double a[N],b[N];
int n,f;
bool cmp(double x)
{
    for(int i=1;i<=n;i++)
    {
        b[i]=b[i-1]+(a[i]-x);
    }
    double Min = 0x3f3f3f3f;
    for(int i=f;i<=n;i++)
    {
        if(b[i-f]<Min)Min=b[i-f];
        if(b[i]-Min>0)return true;
    }
    return false;
}
int main()
{

    cin>>n>>f;
    for(int i=1;i<=n;i++)scanf("%lf",&a[i]);
    double l=1,r=2000;
    while(r-l>1e-5)
    {
        double mid = (l+r)/2;
        if(cmp(mid)) l=mid;
        else r=mid;
    }

    cout<<int(r*1000)<<endl;
    return 0;
}