import java.io.*; import java.util.*; import java.util.stream.*; public class Main { public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); int n = sc.nextInt(); int m = sc.nextInt(); int target = sc.nextInt(); int[] values = new int[n - 1]; for (int i = 0; i < n - 1; i++) { values[i] = sc.nextInt(); } Arrays.sort(values); int left = -1; int right = n - 1; while (right - left > 1) { int x = (left + right) / 2; int up = n - 2; int down = 0; int count = 0; while (down < up && count < m) { if (up == x) { up--; continue; } if (down == x) { down++; continue; } if (values[up] + values[down] > target + values[x]) { count++; up--; down++; } else { down++; } } if (count >= m) { left = x; } else { right = x; } } if (right == n - 1) { System.out.println(-1); } else { System.out.println(values[right]); } } } class Utilities { static String arrayToLineString(Object[] arr) { return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n")); } static String arrayToLineString(int[] arr) { return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new)); } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); StringBuilder sb = new StringBuilder(); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public int[] nextIntArray() throws Exception { return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray(); } public String next() throws Exception { while (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }