#include <bits/stdc++.h>
using namespace std;
const int N = 1e4 + 5;
double a[N];
int n, k;
double check(double tar) {
  double p = 100 - k, to_get = 0, to_lose = 0;
  for (int i = 0; i < n; i++) {
    if (a[i] > tar)
      to_lose += a[i] - tar;
    else
      to_get += tar - a[i];
  }
  return (to_lose * p) / 100.0 - to_get;
}
void solve() {
  double lo = 0, hi = 10000;
  int itr = 150;
  while (itr--) {
    double x = (2 * lo + hi) / 3, y = (lo + 2 * hi) / 3;
    if (abs(check(x)) < abs(check(y)))
      hi = y;
    else
      lo = x;
  }
  printf("%.10lf\n", lo);
}
int main() {
  scanf("%d %d", &n, &k);
  ;
  for (int i = 0; i < n; i++) scanf("%lf", &a[i]);
  solve();
}
