Codefroces62B

#include<iostream>
#include<fstream>
#include<algorithm>
#include<vector>
#include<iomanip>
using namespace std;

vector<int> en;
int n, pre, nex, a=1, b=1, k, tem;
double pr, t, maxi, mini;
bool qw;

void init()
{
    sort(en.begin(), en.end());
    a=1; b=1; nex=1; pre=n-2; maxi=en[n-1]; mini=en[0]; pr=1-((double)k)/(100.0);
};

int main()
{
    cout.precision(10);
    cin>>n>>k;
    for(int i=1;i<=n;i++)
    {
        cin>>tem;
        en.push_back(tem);
    };
    init();
    while(pre>=nex)
    {
        t=(maxi-(double)en[pre])*((double)a);
        qw=true;
        if(mini+(t/b)*pr>(double)en[nex])
        {
            t=(b*((double)en[nex]-mini))/pr;
            qw=false;
        };
        maxi=maxi-t/((double)a);
        mini=mini+t/((double)b)*pr;
        if(qw)
        {
            a++;
            pre--;
        }
        else
        {
            b++;
            nex++;
        };
    };
    if(mini==maxi)
    {
        cout<<mini;
        cin>>n;
        return 0;
    };
    t=(maxi-mini)/((pr)/((double)b)+(1.0)/((double)a));
    cout<<maxi-t/((double)a)<<endl;
    cin>>n;
};