/* 
 *     Author:  srtry
 *     Created: 2025-12-06T13:05:26+09:00
 *     Coding:  utf-8-unix
 */

use proconio::input;
use std::io::{stdout,Write,BufWriter};
use std::collections::BinaryHeap;

fn main() {
    input!{
        n:usize,
        l:[f64;n],
        k:f64
    }

    let out = stdout();
    let mut out = BufWriter::new(out.lock());
    
    // K本の棒を作ることができる長さを二分探索で出す
    let mut right:f64 = l.iter().fold(0.0/0.0, |m,v| v.max(m));
    let mut left:f64 = 0.;
    // let mut left:f64 = u32::MIN as f64;
    let mut ans:f64 = (right + left)/2.;
    let mut sum:f64 = 0.;
    for _ in 0..56 {
        sum = l.iter().map(|&e| (e/ans).trunc()).fold(0.,|sum,e| sum+e);
        if sum<k {
            right=ans;
        } else {
            left=ans;
        }
        ans = (left+right)/2.;
    }
    // write!(out, "{}", sum).unwrap();
    write!(out, "{}", ans).unwrap();
}