#include<cstdio>
#include<cstring>
int a[100010],n,f;
bool att(int x)
{
	int b[100010],q[100010],i,j,k,hd=1,tl=1;
	memset(b,0,sizeof(b));
	memset(q,0,sizeof(q));
	for (i=1;i<=n;i++)
	  b[i]=b[i-1]+a[i]-x;
	for (i=1;i<=n;i++)
	{
		while (i-q[hd+1]>=f&&hd<tl) hd++;
		if (b[i]<b[q[tl]]) q[++tl]=i;
		else 
		  if (i-q[hd]>=f&&b[i]-b[q[hd]]>=0) return 1;
	}
	return 0;
}
int main()
{
	int i,j,k,l,p,q,x,y,z,max,min,r;
	scanf("%d%d",&n,&f);
	for (i=1;i<=n;i++)
	{
		scanf("%d",&a[i]);
		a[i]*=1000;
	}
	max=-1;
	min=10000000;
	for (i=1;i<=n;i++)
	{
		if (a[i]>max) max=a[i];
		if (a[i]<min) min=a[i];
	}
	l=min;
	r=max;
	while (l<r)
	{
		if (att((l+r)/2+1)) l=(l+r)/2+1;
		else r=(l+r)/2;
	}
	printf("%d\n",l);
}