#include <bits/stdc++.h>
int a[50];
int main() {
  int n, m, k;
  scanf("%d%d%d", &n, &m, &k);
  for (int i = 0; i < n; ++i) {
    scanf("%d", &a[i]);
  }
  int cur = k;
  int ans = 0;
  std::sort(a, a + n);
  for (int i = n - 1; i >= 0; --i) {
    if (cur < m) {
      cur += a[i] - 1;
      ans++;
    } else {
      printf("%d", ans);
      return 0;
    }
  }
  if (cur >= m)
    printf("%d", ans);
  else
    printf("-1");
  return 0;
}
