// Codeforces Beta Round #62 B. Energy exchange

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;

int main(){
	int n, k;
	int a[10000];
	while(cin >> n >> k){
		double L = 0, R = 0;
		for(int i=0;i<n;i++){
			scanf("%d", &a[i]);
			R = max(R, (double)a[i]);
		}
		for(int cnt=0;cnt<500;cnt++){
			double mid = 0.5*(L+R);
			double p = 0, q = 0; 
			for(int i=0;i<n;i++){
				if(a[i] < mid) q += mid-a[i];
				else           p += (a[i]-mid)*(1-0.01*k);
			}
			if(q>p) R = mid;
			else    L = mid;
		}
		printf("%.8lf\n", 0.5*(R+L));
	}
}