#include <iostream>
using namespace std;
const int N = 100010;
int a[N];
int n, m;
bool check(double mid) {
int s = 0;
for (int i = 0; i < n; i ++) {
s += a[i] / mid;
if (s >= m) return true;
}
return false;
}
int main() {
cin >> n >> m;
for (int i = 0; i < n; i ++) cin >> a[i];
double l = 0, r = 1e9;
while (r - l > 1e-4) {
double mid = (l + r) / 2;
if (check(mid)) l = mid;
else r = mid;
}
printf("%.2f\n", r);
return 0;
}