#include <bits/stdc++.h>
using namespace std;
int minFilter(vector<int>& v, int m, int k) {
  sort(v.begin(), v.end(), greater<int>());
  int minPlugs = k;
  int filter = 0;
  while (filter < v.size() && minPlugs < m) {
    minPlugs += v[filter] - 1;
    filter++;
  }
  if (minPlugs >= m) return filter;
  return -1;
}
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  vector<int> v(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  int ans = minFilter(v, m, k);
  cout << ans;
  return 0;
}
