#include <bits/stdc++.h>
int main() {
  int n, m, k, i, j, t, c, c1 = 0;
  scanf("%d %d %d", &n, &m, &k);
  int a[n];
  for (i = 0; i < n; i++) scanf("%d", &a[i]);
  if (m <= k)
    printf("0");
  else {
    for (i = 0; i < n; i++) {
      for (j = i; j < n; j++) {
        if (a[i] < a[j]) {
          t = a[i];
          a[i] = a[j];
          a[j] = t;
        }
      }
    }
    c = m - k;
    i = 0;
    while (c > 0) {
      c -= a[i++] - 1;
      c1++;
      if (i == n) break;
    }
    if (c <= 0)
      printf("%d", c1);
    else
      printf("-1");
  }
  return 0;
}
