#include <bits/stdc++.h>
using namespace std;
bool valid(const vector<int>& a, double ans, int k) {
  double t = 0;
  for (int i = 0; i < a.size(); i++) {
    if (a[i] > ans)
      t += (double)a[i] - ans;
    else if (a[i] < ans)
      t -= (ans - (double)a[i]) / (1.0 - (double)k / 100.0);
  }
  if (t < 0) return false;
  return true;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int x, y;
  cin >> x >> y;
  vector<int> vec(x);
  for (int i = 0; i < x; i++) cin >> vec[i];
  double start = 0.0, end = 1000.0, final = 0.0;
  for (int i = 0; i < 50; i++) {
    double mid = (start + end) / 2.0;
    if (valid(vec, mid, (double)y)) {
      start = mid;
      final = mid;
    } else
      end = mid;
  }
  cout << fixed << setprecision(6) << final;
}
