C++ :

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll M=1e5+5;
const ll inf=2e3;
ll n,m;
double a[M],b[M],L=inf,R,ans;

int check(double x){
	for(ll i=1;i<=n;++i) b[i]=b[i-1]+a[i]-x;
	double tmp=inf;
	for(ll i=m;i<=n;++i){
		tmp=min(tmp,b[i-m]);
		if(b[i]-tmp>=0) return 1;
	}
	return 0;
}

void init(){
	freopen("cowfnc.in","r",stdin);
	freopen("cowfnc.out","w",stdout);
}

int main(){
//	init();
	scanf("%lld%lld",&n,&m);
	for(ll i=1;i<=n;++i) scanf("%lf",&a[i]),L=min(L,a[i]),R=max(R,a[i]);
	while(L<=R-1e-4){
		double mid=(L+R)/2;
		if(check(mid)) L=mid;
		else R=mid;
	}
//	printf("%.4lf\n",ans);
	ll tmp=R*1000;
	printf("%lld",tmp);
	return 0;
}