#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
  ll n,k;
  cin >> n >> k;
  vector<ll> a(n);
  for(int i = 0;i < n;i++){
    cin >> a.at(i);
  }
  sort(a.begin(),a.end());
  reverse(a.begin(),a.end());
  ll ans = 0;
  for(int i = 0;i < k;i++){
    if(i * 2 >= n){
      cout << "Impossible" << endl;
      return 0;
    }
    ans += a.at(i * 2);
  }
  cout << ans << endl;
}