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.*;
  import java.util.*;
  
  
  
  public class Test
  {
      final static FastReader fr = new FastReader();
      final static PrintWriter out = new PrintWriter(System.out) ;
      static int mod = 1000000007;
      static long dp[][] ;
  
      static void solve()
      {
        int n  = fr.nextInt();
  
        int arr[] = new int[n] ;
        for (int i = 0 ; i < n ; i++) arr[i] = fr.nextInt();
  
        TreeSet<Integer> rem = new TreeSet<>() ;
        for (int i = 1 ;  i <= n ; i++) rem.add(i) ;
  
        List<Integer> extras = new ArrayList<>() ;
        
        for (int i =0 ; i < n ; i++) {
            if (arr[i] > n){
                extras.add(arr[i]) ;
            } else {
                if (rem.contains(arr[i]))
                rem.remove(arr[i]) ;
                else extras.add(arr[i]) ;
            }
        }
  
        Collections.sort(extras);
  
        int i = 0 ;
        int ans = 0 ;
  
        
  
        for (int x: rem)
        {
            int curr = x;
            if ((extras.get(i)-1)/2 < curr) {
                out.println(-1);
                return;
            }
            ans++ ;
            i++ ;
        }
  
        out.println(ans);
  
  
  
      }
  
      public static void main(String[] args)
      {
          int t =  fr.nextInt();
  
          while (t-- > 0)
          {
              solve() ;
          }
          out.close() ;
      }
  
      static class Pair{
          int x;
          int y ;
  
          Pair(int x, int y){
              this.x = x ;
              this.y= y ;
          }
      }
  
      static long gcd(long a, long b)
      {
          if (b == 0) return a ;
          return gcd(b,  a%b) ;
      }
  
      static long lcm(long a, long b)
      {
          long lcm = (a * b)/gcd(a, b) ;
          return lcm ;
      }
  
      static List<Integer> seive(int n)
      {
          // all are false by default
          // false -> prime, true -> composite
          boolean nums[] = new boolean[n+1] ;
  
          for (int i = 2 ; i <= Math.sqrt(n); i++)
          {
              if  (nums[i] == false)
              {
                  for (int j = i*i ; j <= n ; j += i)
                  {
                      nums[j] = true ;
                  }
              }
          }
  
          List<Integer> primes = new ArrayList<>();
  
          for (int i = 2 ; i <= n ;i++)
          {
              if (nums[i] == false) primes.add(i) ;
          }
  
          return primes ;
      }
  
      static boolean isVowel(char ch)
      {
          if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u')
              return true ;
          return false ;
      }
  
      static long fastpower(long a, long b)
      {
          long ans = 1 ;
          while (b > 0)
          {
              if ((b & 1) != 0) ans *= a ;
              a *= a  ;
              b >>= 1 ;
          }
          return ans ;
      }
  
      static int lower_bound(List<Long> arr, long key)
      {
          int pos = Collections.binarySearch(arr, key) ;
          if (pos < 0)
          {
              pos = - (pos + 1) ;
          }
          return pos ;
      }
  
      static int upper_bound(List<Long> arr, long key)
      {
          int pos = Collections.binarySearch(arr, key);
          pos++ ;
          if (pos < 0)
          {
              pos = -(pos) ;
          }
          return pos ;
      }
  
      static void printArr(int arr[])
      {
          int n = arr.length ;
          for (int i = 0 ; i < n ; i++) out.print(arr[i] + " ");
          out.println() ;
      }
  
      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;
          }
      }
  
  
  }