#include <bits/stdc++.h>
using namespace std;
int n, k;
vector<double> a;
bool ispos(double x) {
  double up = 0, down = 0;
  for (int i = 0; i < n; i++) {
    if (a[i] > x) {
      up += a[i] - x;
    } else {
      down += x - a[i];
    }
  }
  return up * (100 - k) >= down * 100;
}
int main() {
  cin >> n >> k;
  a.resize(n);
  double sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    sum += a[i];
  }
  double l = 0, r = sum / n;
  while (abs(r - l) > 1e-10) {
    double m = (l + r) / 2;
    if (ispos(m))
      l = m;
    else
      r = m;
  }
  printf("%.7f\n", l);
  return 0;
}
