#include <iostream>
#include <stdio.h>
#include <string.h>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <numeric>
#include <queue>
#include <cassert>
#include <cmath>
#include <bitset>
using namespace std;

int main() {
  int n, k;
  cin >> n >> k;
  int x;
  cin >> x;
  vector<int> a(n-1);
  for (int i = 0; i < n-1; i++) cin >> a[i];
  sort(a.begin(), a.end());

  int ng = -1;
  int ok = n-1;
  while (ng+1 < ok) {
    int m = (ng+ok)/2;
    //printf("ng = %d, ok = %d, m = %d\n", ng, ok, m);
    vector<int> b;
    for (int i = 0; i < n-1; i++)
      if (i != m) b.push_back(a[i]);
    //cout << "b : "; for (auto bb : b) cout << bb << " "; cout << endl;
    int cnt = 0;
    int l = 0, r = n-3;
    while (l < r) {
      if (b[l]+b[r] > x+a[m]) {
        l++;
        r--;
        cnt++;
      }
      else {
        l++;
      }
    }
    //cout << "cnt = " << cnt << endl;
    if (cnt < k) ok = m;
    else ng = m;
  }
  if (ok == n-1) cout << -1 << endl;
  else cout << a[ok] << endl;
}