#include <bits/stdc++.h>

using namespace std;

ifstream fin("transport.in");
ofstream fout("transport.out");


int rotunjire(float y)
{
    if(y-(int(y))>0.5)
    {return int(y)+1;}
    else return int(y);
}

int n, k, suma, u;

int main()
{
    fin>>n>>k;
    for(int i=1;i<=n;i++){fin>>u;suma+=u;}
    float x;
    x=(float)suma/k;
    //cout<<suma<<" "<<k<<endl;
    //cout<<x<<" "<<int(x)<<" "<<(x-int(x));
    fout<<rotunjire(x)+k/2;

    return 0;
}