#include <bits/stdc++.h>
using namespace std;
double ener[10010];
int cmp(double a, double b) { return a > b; }
int main() {
  int n, k;
  while (~scanf("%d%d", &n, &k)) {
    bool flag = false;
    for (int i = 0; i < n; i++) {
      scanf("%lf", &ener[i]);
      if (i >= 1) {
        if (ener[i] != ener[i - 1]) {
          flag = true;
        }
      }
    }
    if (n == 1 || !flag) {
      printf("%.9f\n", ener[0]);
      continue;
    }
    sort(ener, ener + n, cmp);
    double l = ener[n - 1];
    double r = ener[0];
    double mid;
    double ans;
    while (r - l > 1e-9) {
      bool flag = true;
      double cur_ener = 0;
      mid = (l + r) / 2;
      for (int i = 0; i < n; i++) {
        if (ener[i] - mid >= 1e-9)
          cur_ener += (ener[i] - mid);
        else {
          double dis = 1.0 * (mid - ener[i]) * 100 / (100 - k);
          if (dis - cur_ener > 1e-9) {
            flag = false;
            break;
          } else
            cur_ener -= dis;
        }
      }
      if (flag) {
        ans = mid;
        l = mid;
      } else
        r = mid;
    }
    printf("%.9f\n", ans);
  }
  return 0;
}
