#include <bits/stdc++.h>
using namespace std;
void merger(int A[], int L, int M, int R) {
  int n1 = M - L + 1;
  int n2 = R - M;
  int left[n1], right[n2];
  int i = 0, j = 0, k = L;
  for (i = 0; i < n1; i++) left[i] = A[i + L];
  for (i = 0; i < n2; i++) right[i] = A[i + M + 1];
  i = 0;
  while (i < n1 && j < n2) {
    if (left[i] <= right[j]) {
      A[k] = left[i];
      i++;
    } else {
      A[k] = right[j];
      j++;
    }
    k++;
  }
  while (i < n1) {
    A[k] = left[i];
    i++;
    k++;
  }
  while (j < n2) {
    A[k] = right[j];
    j++;
    k++;
  }
}
void merge_sort(int A[], int L, int R) {
  if (L < R) {
    int M = (L + R) / 2;
    merge_sort(A, L, M);
    merge_sort(A, M + 1, R);
    merger(A, L, M, R);
  }
}
int main() {
  int n, m, k, i, ans = 0;
  scanf("%d%d%d", &n, &m, &k);
  int A[n];
  for (i = 0; i < n; i++) scanf("%d", &A[i]);
  merge_sort(A, 0, n - 1);
  i = n - 1;
  while (k < m && i >= 0) {
    k += A[i] - 1;
    i--;
    ans++;
  }
  if (k < m)
    printf("-1");
  else
    printf("%d", ans);
  return 0;
}
