#include <bits/stdc++.h>
using namespace std;
int toInt(string s) {
  int res;
  stringstream ss;
  ss << s;
  ss >> res;
  return res;
}
const int inf = 1 << 27;
bool ok(double x, vector<int> a, int k) {
  double luck = 0;
  double amari = 0;
  for (int i = (0); i < ((int((a).size()))); ++i) {
    if ((double)a[i] > x) {
      amari += (double)a[i] - x;
    } else
      luck += x - (double)a[i];
  }
  if (amari * (100 - k) / 100 > luck)
    return true;
  else
    return false;
}
int main(void) {
  int n, k;
  cin >> n >> k;
  vector<int> a;
  int sum = 0;
  for (int i = (0); i < (n); ++i) {
    int tmp;
    cin >> tmp;
    a.push_back(tmp);
    sum += tmp;
  }
  double lo = 0, hi = (double)sum / n;
  for (int i = (0); i < (100); ++i) {
    double ave = (lo + hi) / 2;
    if (ok(ave, a, k)) {
      lo = ave;
    } else
      hi = ave;
  }
  cout.precision(20);
  cout << lo << endl;
  return 0;
}
