#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:100000000")
using namespace std;
int n, m, k, i, j, a[55], cnt;
int main() {
  cin >> n >> m >> k;
  for (i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  reverse(a, a + n);
  i = 0;
  while (k < m && i < n) {
    cnt++;
    k += a[i] - 1;
    i++;
  }
  if (i == n && k < m)
    printf("-1\n");
  else
    printf("%d\n", cnt);
  return 0;
}
