#include<bits/stdc++.h>
using namespace std;
#define MAXN 1000100
#define ll long long
#define inf 1000000000
int n, m, cnt, a[MAXN], k, dp[MAXN];
double eps = 1e-6, sum[MAXN], b[MAXN];
struct node
{
    int left, right;
    double Max, lazy;
    node *ch[2];
}pool[2*MAXN], *root;
void buildtree(node *p, int left, int right)
{
    p->left = left; p->right = right;
    if(left == right) return ;
    node *lson = &pool[++cnt], *rson = &pool[++cnt];
    p->ch[0] = lson; p->ch[1] = rson;
    int mid = (left + right) / 2;
    buildtree(lson, left, mid); buildtree(rson, mid+1, right);
}
void init(node *p)
{
    p->Max = -inf;
    p->lazy = 0;
    if(p->left == p->right) return ;
    init(p->ch[0]); init(p->ch[1]);
}
void push(node *p)
{
    if(p->lazy == 0) return ;
    if(p->ch[0]) p->ch[0]->lazy += p->lazy;
    if(p->ch[1]) p->ch[1]->lazy += p->lazy;
    p->Max += p->lazy;
    p->lazy = 0;
}
void change(node *p, int left, int right, double s)
{
    if(left > right) return ;
    push(p);
    if(p->left == left && p->right == right)
    {
        p->lazy += s;
        return ;
    }
    push(p);
    if(p->ch[0]->right >= right) change(p->ch[0], left, right, s);
    else if(p->ch[1]->left <= left) change(p->ch[1], left, right, s);
    else{
        change(p->ch[0], left, p->ch[0]->right, s);
        change(p->ch[1], p->ch[1]->left, right, s);
    }
    if(p->ch[0]) push(p->ch[0]);
    if(p->ch[1]) push(p->ch[1]);
    p->Max = max(p->ch[0]->Max, p->ch[1]->Max);
}
void ask(node *p, int left, int right, double s)
{
    if(left > right) return ;
    push(p);
    if(p->left == left && p->right == right)
    {
        p->Max = max(p->Max, s);
        return ;
    }
    push(p);
    if(p->ch[0]->right >= right) ask(p->ch[0], left, right, s);
    else ask(p->ch[1], left, right, s);
    if(p->ch[0]) push(p->ch[0]);
    if(p->ch[1]) push(p->ch[1]);
    p->Max = max(p->ch[0]->Max, p->ch[1]->Max);
}
int query(node *p, int left, int right)
{
    // if(left > right) return -inf;
    push(p);
    if(p->left == left && p->right == right) return p->Max;
    if(p->ch[0]->right >= right) return query(p->ch[0], left, right);
    else if(p->ch[1]->left <= left) return query(p->ch[1], left, right);
    else{
        return max(query(p->ch[0], left, p->ch[0]->right), query(p->ch[1], p->ch[1]->left, right));
    }
}
int solve(node *p)
{
    push(p);
    if(p->left == p->right) return p->left;
    if(p->ch[0]) push(p->ch[0]);
    if(p->ch[1]) push(p->ch[1]);
    p->Max = max(p->ch[0]->Max, p->ch[1]->Max);
    if(p->Max < 0) return 0;
    if(p->ch[1]->Max >= 0) return solve(p->ch[1]);
    else return solve(p->ch[0]);
}
bool check(double mid)
{
    for(int i=1;i<=n;i++) b[i] = a[i] - mid, sum[i] = sum[i-1] + b[i];//, printf("%lf ",b[i]);
    // cout<<endl;
    init(root);
    int mx = 0;
    for(int i=1;i<=n;i++)
    {
        change(root, 1, mx, b[i]);
        if(sum[i] < 0) 
        {
            dp[i] = 0;
            continue;
        }
        dp[i] = 1;
        if(query(root, 1, n) < 0);
        else{
            dp[i] = solve(root) + 1;
        }       
        // if(dp[i] > mx) change(root, dp[i], dp[i], inf);
        mx = max(mx, dp[i]);
        ask(root, dp[i], dp[i], 0);
    }
    // for(int i=1;i<=n;i++) printf("%d ",dp[i]);
    // printf("%lf %d\n",mid,dp[n]);
    return dp[n] >= k;
}
int main()
{
    int mn = inf, mx = -inf;
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++) scanf("%d",&a[i]), mn = min(mn, a[i]), mx = max(mx, a[i]);
    root = &pool[++cnt];
    buildtree(root, 1, n);
    double Left = mn, Right = mx, mid, ans = mn;
    while(Right-Left >= eps)
    {
        mid = (Left + Right) / 2;
        if(check(mid) == true) 
            ans = mid, Left = mid;
        else Right = mid;
        // cout<<mid<<endl;
    }
    // check(1.687500);
    printf("%.8lf\n",ans);
    
    return 0;
}