#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[55];
  int tot, i, j, n, m, k;
  int res, sum;
  while (scanf("%d %d %d", &n, &m, &k) != EOF) {
    sum = 0;
    res = 0;
    for (i = 0; i < n; i++) {
      scanf("%d", &a[i]);
      sum += a[i];
    }
    if (sum + k - n < m) {
      printf("-1\n");
      continue;
    }
    sort(a, a + n);
    tot = k;
    i = n - 1;
    while (tot < m && i >= 0) {
      res++;
      tot += a[i--] - 1;
    }
    printf("%d\n", res);
  }
  return 0;
}
