#include <bits/stdc++.h>
using namespace std;
const long long inf = INT_MAX;
const long double ep = 0.0000001;
const long double pi = acos(-1.0);
const long long md = 1e9 + 7;
void val(char &x) {
  if (x == '6')
    x = '1';
  else if (x == '7')
    x = '2';
  else if (x == '8')
    x = '3';
  else if (x == '9')
    x = '4';
  else if (x == 'T')
    x = '5';
  else if (x == 'J')
    x = '6';
  else if (x == 'Q')
    x = '7';
  else if (x == 'K')
    x = '8';
  else
    x = '9';
}
void solve() {
  int n, m, k;
  cin >> n >> m >> k;
  vector<int> v;
  int s = 0;
  for (long long i = 0; i < n; ++i) {
    int x;
    cin >> x;
    v.push_back(x);
    s += x;
  }
  sort(v.begin(), v.end());
  if (m - k <= 0)
    cout << 0;
  else {
    int c = 1;
    int s = k;
    for (long long i = v.size() - 1; i > -1; --i) {
      s += v[i];
      s--;
      if (s >= m) {
        cout << c;
        return;
      }
      c++;
    }
    cout << -1;
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  int t = 1;
  while (t--) solve();
}
