#include <cstdio>
#include <cstring>
#include <iostream>

using namespace std;

const int N = 100010;

int n, f;
double s[N], a[N];

bool check(double avg)
{
    for (int i = 1; i <= n; i ++ ) s[i] = s[i - 1] + a[i] - avg;

    double mins = 0;
    for (int k = f; k <= n; k ++ )
    {
        mins = min(s[k - f], mins);
        if (s[k] >= mins) return true;
    }

    return false;    
}

int main()
{
    cin >> n >> f;
    double l = 0, r = 0;
    for (int i = 1; i <= n; i ++ )
    {
        scanf("%lf", &a[i]);
        r = max(r, a[i]);
    }

    while (r - l > 1e-5)
    {
        double mid = (l + r) / 2;
        if (check(mid)) l = mid;
        else r = mid;
    }

    printf("%d", (int)(r * 1000));

    return 0;
}