#include<bits/stdc++.h>

using namespace std;

const int maxn=1e5+10;

int n,l;

double sz[maxn],f[maxn];

bool pd(double x)

{

    for(int i=1;i<=n;++i)f[i]=sz[i]-x;

    double mn=0;

    for(int i=1;i<l;++i)f[i]=f[i-1]+f[i];

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

    {

        f[i]=f[i]+f[i-1];

        mn=min(mn,f[i-l]);

        if(f[i]>=mn)return 1;

    }

    return 0;

}

int main()

{

    scanf("%d%d",&n,&l);

    for(int i=1;i<=n;++i)scanf("%lf",sz+i);

    double l=0,r=2000;

    while(l+1e-8<r)

    {

        double mid=(l+r)/2;

        if(pd(mid))l=mid;

        else r=mid;

    }

    cout<<int(r*1000);

    return 0;

}