description: Paprika loves permutations. She has an array a_1, a_2, ..., a_n. She wants to make the array a permutation of integers 1 to n.
  
  In order to achieve this goal, she can perform operations on the array. In each operation she can choose two integers i (1 ≤ i ≤ n) and x (x > 0), then perform a_i := a_i mod x (that is, replace a_i by the remainder of a_i divided by x). In different operations, the chosen i and x can be different.
  
  Determine the minimum number of operations needed to make the array a permutation of integers 1 to n. If it is impossible, output -1.
  
  A permutation is an array consisting of n distinct integers from 1 to n in arbitrary order. For example, [2,3,1,5,4] is a permutation, but [1,2,2] is not a permutation (2 appears twice in the array) and [1,3,4] is also not a permutation (n=3 but there is 4 in the array).
  
  Input
  
  Each test contains multiple test cases. The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases. Description of the test cases follows.
  
  The first line of each test case contains an integer n (1 ≤ n ≤ 10^5).
  
  The second line of each test case contains n integers a_1, a_2, ..., a_n. (1 ≤ a_i ≤ 10^9).
  
  It is guaranteed that the sum of n over all test cases does not exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case, output the minimum number of operations needed to make the array a permutation of integers 1 to n, or -1 if it is impossible.
  
  Example
  
  Input
  
  
  4
  2
  1 7
  3
  1 5 4
  4
  12345678 87654321 20211218 23571113
  9
  1 2 3 4 18 19 5 6 7
  
  
  Output
  
  
  1
  -1
  4
  2
  
  Note
  
  For the first test, the only possible sequence of operations which minimizes the number of operations is: 
  
    * Choose i=2, x=5. Perform a_2 := a_2 mod 5 = 2. 
  
  
  
  For the second test, it is impossible to obtain a permutation of integers from 1 to n.
solution:     //import java.io.IOException;
  
      import java.io.IOException;
      import java.io.InputStream;
      import java.io.PrintWriter;
      import java.util.*;
  
      public class PaprikaandPermutation {
          static InputReader inputReader=new InputReader(System.in);
          static void solve() {
              int n = inputReader.nextInt();
              TreeMap<Long, Integer> treeMap = new TreeMap<>();
              long arr[] = new long[n];
              for (int i=0;i<n;i++)
              {
                  arr[i]=inputReader.nextLong();
              }
              HashSet<Long>present=new HashSet<>();
              for (long ele:arr) {
                  if (ele>n) {
                      treeMap.put(ele, treeMap.getOrDefault(ele, 0) + 1);
                  }
                  else {
                      if (!present.contains(ele)) {
                          present.add(ele);
                      }
                      else
                      {
                          treeMap.put(ele, treeMap.getOrDefault(ele, 0) + 1);
                      }
                  }
              }
              int count=0;
              for (long i=1;i<=n;i++)
              {
                  if (present.contains(i))
                  {
                      continue;
                  }
                  else
                  {
                      long no=2*i+1;
                      Long key=treeMap.ceilingKey(no);
                      if (key==null)
                      {
                          out.println(-1);
                          return;
                      }
                      count++;
                      treeMap.put(key,treeMap.getOrDefault(key,0)-1);
                      if (treeMap.get(key)==0)
                      {
                          treeMap.remove(key);
                      }
                  }
              }
              out.println(count);
          }
          static PrintWriter out=new PrintWriter((System.out));
          public static void main(String args[])throws IOException
          {
              int t=inputReader.nextInt();
              while (t-->0) {
                  solve();
              }
                  out.close();
          }
  
          static void Sort(int arr[])
          {
              List<Integer>list=new ArrayList<>();
              for (int ele:arr)
              {
                  list.add(ele);
              }
              Collections.sort(list);
              for (int i=0;i<list.size();i++)
              {
                  arr[i]=list.get(i);
              }
          }
          static void sortDec(int arr[])
          {
              int len=arr.length;
              List<Integer>list=new ArrayList<>();
              for(int ele:arr)
              {
                  list.add(ele);
              }
              Collections.sort(list,Collections.reverseOrder());
              for(int i=0;i<len;i++) {
                  arr[i] = list.get(i);
              }
          }
          static class InputReader {
  
              private InputStream stream;
              private byte[] buf = new byte[8192];
              private int curChar, snumChars;
              private SpaceCharFilter filter;
  
              public InputReader(InputStream stream) {
                  this.stream = stream;
              }
  
              public int snext() {
                  if (snumChars == -1)
                      throw new InputMismatchException();
                  if (curChar >= snumChars) {
                      curChar = 0;
                      try {
                          snumChars = stream.read(buf);
                      } catch (IOException e) {
                          throw new InputMismatchException();
                      }
                      if (snumChars <= 0)
                          return -1;
                  }
                  return buf[curChar++];
              }
  
              public int nextInt() {
                  int c = snext();
                  while (isSpaceChar(c))
                      c = snext();
                  int sgn = 1;
                  if (c == '-') {
                      sgn = -1;
                      c = snext();
                  }
                  int res = 0;
                  do {
                      if (c < '0' || c > '9')
                          throw new InputMismatchException();
                      res *= 10;
                      res += c - '0';
                      c = snext();
                  } while (!isSpaceChar(c));
                  return res * sgn;
              }
  
              public long nextLong() {
                  int c = snext();
                  while (isSpaceChar(c))
                      c = snext();
                  int sgn = 1;
                  if (c == '-') {
                      sgn = -1;
                      c = snext();
                  }
                  long res = 0;
                  do {
                      if (c < '0' || c > '9')
                          throw new InputMismatchException();
                      res *= 10;
                      res += c - '0';
                      c = snext();
                  } while (!isSpaceChar(c));
                  return res * sgn;
              }
  
              public int[] nextIntArray(int n) {
                  int a[] = new int[n];
                  for (int i = 0; i < n; i++)
                      a[i] = nextInt();
                  return a;
              }
  
              public String readString() {
                  int c = snext();
                  while (isSpaceChar(c))
                      c = snext();
                  StringBuilder res = new StringBuilder();
                  do {
                      res.appendCodePoint(c);
                      c = snext();
                  } while (!isSpaceChar(c));
                  return res.toString();
              }
  
              public boolean isSpaceChar(int c) {
                  if (filter != null)
                      return filter.isSpaceChar(c);
                  return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
              }
  
              public interface SpaceCharFilter {
                  public boolean isSpaceChar(int ch);
              }
          }
      }
  