#include<bits/stdc++.h>
using namespace std;
int n,a[200100],m;
#define db double
const db eps=1e-10;
db f[200100];int p[201000],rk[201000],tr[201000];
void ad(int x,int z){for(;x<=n+1;x+=(x&-x))tr[x]=max(tr[x],z);}
int ask(int x){int s=-1e9;for(;x;x-=(x&-x))s=max(s,tr[x]);return s;}
bool ff;
bool chk(db X){
    for(int i=1;i<=n;i++)f[i]=f[i-1]+(a[i]-X);
    for(int i=0;i<=n;i++)p[i]=i,tr[i]=-1e9;tr[n+1]=-1e9;
    sort(p,p+n+1,[&](int x,int y){if(abs(f[x]-f[y])>eps)return f[x]<f[y];return x<y;});
    for(int i=0;i<=n;i++)rk[p[i]]=i+1;
    for(int i=0;i<=n;i++){
        int t=0;
        if(i)t=ask(rk[i])+1;
        ad(rk[i],t);
        if(i==n)return t>=m;
    }
    return 0;
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)scanf("%d",&a[i]);
    db l=0,r=1e3;int t=50;while(t--){
        db mi=(l+r)/2;
        if(chk(mi))l=mi;
        else r=mi;
    }
    ff=1;chk(l);
    printf("%.7lf",l);
    return 0;
}