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.util.*;
  import java.util.regex.Pattern;
  
  import javax.lang.model.element.Element;
  import javax.sql.rowset.spi.SyncResolver;
  import javax.swing.text.TableView;
  import javax.swing.text.StyledEditorKit.BoldAction;
  
  import java.io.*;
  import java.nio.file.attribute.GroupPrincipal;
  import java.nio.file.attribute.PosixFilePermission;
  import java.sql.PseudoColumnUsage;
  
  public class Solution {
  
      static FastReader fr = new FastReader();
      static final Random random = new Random();
      static long mod = 1000000007L;
  
          public static void main(String args[]) throws IOException {
          
          // int t= fr.nextInt();
          StringBuilder str = new StringBuilder();
          int t= fr.nextInt();
  
          while(t-->0)
          {   
              int n = fr.nextInt();
             int[] arr = new int[n];
             HashSet<Integer> pNum = new HashSet<Integer>();
             PriorityQueue<Integer> extra = new PriorityQueue<Integer>();
  
             for(int i=0;i<n;i++)
             {
                      
                  arr[i] = fr.nextInt();
                  if(arr[i] <=n && !pNum.contains(arr[i]))
                  {   
                      pNum.add(arr[i]);
                      
                  }
                  else
                  extra.add(arr[i]);
             }
             int min = extra.size();
          //    System.out.println(extra);
          boolean notPoss = false;
             for(int i=1;i<=n;i++)
             {
                 if(!pNum.contains(i))
                 {
                      int num = extra.poll();
                      if(num-i<=i)
                      {
                          str.append(-1+"\n");
                          notPoss = true;
                          break;
                      }
  
                 }
             }
             if(notPoss)
             continue;
             
             str.append(min+"\n");
          
          
          }
          System.out.println(str.toString());
  
      }
  
      static void printArray(int[] a) {
          System.out.println();
          for (int i = 0; i < a.length; i++) {
  
              System.out.println(a[i] );
              // System.out.println();
          }
          System.out.println();
      }
  
      static int max(int a, int b) {
          if (a < b)
              return b;
          return a;
      }
  
      static void ruffleSort(int[] a) {
          int n = a.length;
          for (int i = 0; i < n; i++) {
              int oi = random.nextInt(n), temp = a[oi];
              a[oi] = a[i];
              a[i] = temp;
          }
          Arrays.sort(a);
      }
  
      static <E> void print(E res) {
          System.out.println(res);
      }
  
      static int gcd(int a, int b) {
          if (b == 0) {
              return a;
          }
          return gcd(b, a % b);
      }
  
      static int lcm(int a, int b) {
          return (a / gcd(a, b)) * b;
      }
  
      static int abs(int a) {
          if (a < 0)
              return -1 * a;
          return a;
      }
  
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
  
          int[] readintarray(int n) {
              int res[] = new int[n];
              for (int i = 0; i < n; i++)
                  res[i] = nextInt();
              return res;
          }
  
          long[] readlongarray(int n) {
              long res[] = new long[n];
              for (int i = 0; i < n; i++)
                  res[i] = nextLong();
              return res;
          }
      }
  
  }
  