#include <bits/stdc++.h>
using namespace std;
bool absAscend(long int i, long int j) { return abs(i) < abs(j); }
void showVector(vector<long int> &a, string i) {
  cout << "\n" << i << "\n";
  for (std::vector<long int>::iterator it = a.begin(); it != a.end(); ++it)
    cout << ' ' << *it;
}
int main() {
  int k, n, i = 0, tmp;
  vector<long> a;
  vector<long>::iterator it;
  cin >> n >> k;
  while (i < n && cin >> tmp) {
    a.push_back(tmp);
    i++;
  }
  sort(a.begin(), a.end());
  it = a.end();
  if (((int)a.size()) < k) {
    cout << -1;
    return 0;
  }
  it -= k;
  cout << *it << " " << *it;
  return 0;
}
