#include<bits/stdc++.h>
#define int long long
#define mod 998244353ll
#define pii pair<int,int>
#define fi first
#define se second
#define mems(x,y) memset(x,y,sizeof(x))
#define pb push_back
#define db double
using namespace std;
const int maxn=200010;
const int inf=1e18;
const db eps=1e-10;
inline int read(){
	int x=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+(ch-48);ch=getchar();}
	return x*f;
}
bool Mbe;

int n,k;
db a[maxn];
db lsh[maxn];int len;
#define lb(x) (x&(-x))
int tree[maxn];
void upd(int x,int w){
	while(x<=len)tree[x]=max(tree[x],w),x+=lb(x);
}
int que(int x){
	int res=0;
	while(x)res=max(res,tree[x]),x-=lb(x);
	return res;
}
bool check(db x){
	db sum=0;
	lsh[len=1]=0;
	for(int i=1;i<=n;i++)sum+=a[i]-x,lsh[++len]=sum;
	sort(lsh+1,lsh+len+1),len=unique(lsh+1,lsh+len+1)-lsh-1;
	for(int i=1;i<=len;i++)tree[i]=0;
	sum=0.0;
	for(int i=1;i<=n;i++){
		sum+=a[i]-x;
		if(sum>0){
			int p=lower_bound(lsh+1,lsh+len+1,sum)-lsh;
			int val=que(p-1)+1;upd(p,val);
		}
	}
	// cout<<x<<" "<<que(n)<<"\n";
	return que(n)>=k;
}
void work(){
	n=read();k=read();
	for(int i=1;i<=n;i++)a[i]=read();
	db l=1,r=1000.0;
	while(r-l>eps){
		db mid=(l+r)/2.0;
		if(!check(mid))r=mid;
		else l=mid;
	}
	printf("%.10lf\n",l);
}

// \
444

bool Med;
int T;
signed main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	
//	ios::sync_with_stdio(0);
//	cin.tie(0);cout.tie(0);
	
//	cerr<<(&Mbe-&Med)/1048576.0<<" MB\n";
	
	T=1;
	while(T--)work();
}