#include <bits/stdc++.h>
using namespace std;
int N, K;
int arr[10005];
inline bool p(double eq) {
  double val, generated = 0, absorbed = 0;
  for (int i = 0; i < N; i++) {
    val = (double)arr[i] - eq;
    if (val > 0)
      generated += val;
    else
      absorbed -= val;
  }
  generated *= (K / 100.0);
  return generated - absorbed > -1e-9;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> N >> K;
  for (int i = 0; i < N; i++) cin >> arr[i];
  K = 100 - K;
  double lo = 0, hi = 1000, ans = -1, mid;
  int rep = 60;
  while (rep--) {
    mid = lo + (hi - lo) / 2;
    if (p(mid)) {
      ans = lo;
      lo = mid + 1e-9;
    } else {
      hi = mid - 1e-9;
    }
  }
  printf("%.9f\n", ans);
  return 0;
}
