#include <bits/stdc++.h>
using namespace std;
int n, k, aa;
double a[10007];
bool ok(double x) {
  double sum = 0, need = 0;
  for (int i = 0; i < n; ++i) {
    x < a[i] ? sum += a[i] - x - (a[i] - x)* k / 100 : need += x - a[i];
  }
  return sum - need + 1e-7 > 0;
}
int main() {
  cin >> n >> k;
  for (int i = 0; i < n; ++i) {
    scanf("%d", &aa);
    a[i] = aa;
  }
  double st = 0, en = 100000;
  while (st + 1e-7 < en) {
    double mid = (st + en) / 2;
    ok(mid) ? st = mid : en = mid;
  }
  printf("%.6f", st);
}
