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: // हर हर महादेव
  import java.util.*;
  import java.lang.*;
  import java.io.*;
  import java.math.BigInteger;
  import java.text.DecimalFormat;
  
  public final class Solution {
  
      static int inf = Integer.MAX_VALUE;
      static long mod = 1000000000 + 7;
  
   static void ne(Scanner sc, BufferedWriter op) throws Exception { 
      int n=sc.nextInt();
      int[] arr = new int[n];
       ArrayList<Integer> list= new ArrayList<>();
      HashSet<Integer> st= new HashSet<>();
      int[] ans= new int[n+1];
      for(int i=0;i<n;i++){
          arr[i]=sc.nextInt();
          if(st.contains(arr[i])){
              list.add(arr[i]);
          }
          st.add(arr[i]);
  
      }
      for(int i=1;i<=n;i++){
          if(st.contains(i)){
              st.remove(i);
              ans[i]=i;
          }
      }
  
      for(int nn:st){
        list.add(nn);
      }
      
      Collections.sort(list);
      int c=0;
      for(int i=1;i<=n;i++){
          if(ans[i]!=i){
              ans[i]=list.get(c++);
          }
      }
      int count=0;
      
      boolean f=true;
      HashMap<Integer,Integer> hm = new HashMap<>();
      for(int i=1;i<=n;i++){
         if(ans[i]==i){
             count++;
         }else{
             hm.put(i,ans[i]);
         }
      }
      for(int k:hm.keySet()){
          int no=hm.get(k)-k;
          if(hm.get(k)%no!=k){
              f=false;
              break;
          }
      }
      if(f){
         int val=n-count;
         op.write(val+"\n");
      }else{
         op.write("-1\n");
      }
  
     
  
  
         
      
    
           
   }
  
    static int gcd(int a, int b)
      {
          if (a == 0)
              return b; 
          return gcd(b % a, a); 
      }
       
  
      public static void main(String[] args) throws Exception {
          BufferedWriter op = new BufferedWriter(new OutputStreamWriter(System.out));
          // Reader sc = new Reader();
          Scanner sc= new Scanner(System.in);
          int t = sc.nextInt();
          while (t-->0){ ne(sc, op); }
          
          // ne(sc,op);
             
                     
          op.flush();
      }
  
      static void print(Object o) {
          System.out.println(String.valueOf(o));
      }
      static int[] toIntArr(String s){
          int[] val= new int[s.length()];
          for(int i=0;i<s.length();i++){
              val[i]=s.charAt(i)-'a';
          }
          return val;
      }
  
      static void  sort(int[] arr){
          ArrayList<Integer> list= new ArrayList<>();
          for(int i=0;i<arr.length;i++){
              list.add(arr[i]);
  
          }
          Collections.sort(list);
          for(int i=0;i<arr.length;i++){
              arr[i]=list.get(i);
          }
      }
         static void  sort(long[] arr){
          ArrayList<Long> list= new ArrayList<>();
          for(int i=0;i<arr.length;i++){
              list.add(arr[i]);
  
          }
          Collections.sort(list);
          for(int i=0;i<arr.length;i++){
              arr[i]=list.get(i);
          }
      }
  
  }
  
  
  
  // return -1 to put no ahed in array
  class pair {
      int  xx;
      int yy;
      pair(int xx, int yy ) {
          this.xx = xx;
          this.yy = yy;
      }
  }
  
  
  class sortY implements Comparator<pair> {
      public int compare(pair p1, pair p2) {
          if (p1.yy > p2.yy) {
              return 1;
          } else if (p1.yy == p2.yy) {
              if (p1.xx > p2.xx) {
                  return 1;
              } else if (p1.xx < p2.xx) {
                  return -1;
              }
              return 0;
  
          }
          return -1;
      }
  }
  
  class sortX implements Comparator<pair> {
      public int compare(pair p1, pair p2) {
          if (p1.xx > p2.xx) {
              return 1;
          } else if (p1.xx == p2.xx) {
              if (p1.yy > p2.yy) {
                  return 1;
              } else if (p1.yy < p2.yy) {
                  return -1;
              }
              return 0;
  
          }
          return -1;
      }
  }
  
  class debug {
  
      static void print1d(long[] arr) {
          System.out.println();
          for (int i = 0; i < arr.length; i++) {
              System.out.print(arr[i] + " ");
          }
  
      }
  
      static void print1d(int[] arr) {
          System.out.println();
          for (int i = 0; i < arr.length; i++) {
              System.out.println(i+" = "+arr[i]);
          }
  
      }
  
      static void print1d(boolean[] arr) {
          System.out.println();
          for (int i = 0; i < arr.length; i++) {
              System.out.println(i + "= " + arr[i]);
          }
  
      }
  
      static void print2d(int[][] arr) {
          System.out.println();
          int n = arr.length;
          int n2 = arr[0].length;
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < n2; j++) {
                  System.out.print(arr[i][j] + " ");
              }
              System.out.println();
          }
  
      }
  
      static void print2d(long[][] arr) {
          System.out.println();
          int n = arr.length;
          int n2 = arr[0].length;
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < n2; j++) {
                  System.out.print(arr[i][j] + " ");
              }
              System.out.println();
          }
  
      }
       static void printPair(ArrayList<pair> list) {
          if(list.size()==0){
              System.out.println("empty list");
              return;
          }
         System.out.println();
         for(int i=0;i<list.size();i++){
            System.out.println(list.get(i).xx+"-"+list.get(i).yy);
         }
      }
  
  }
  
  class Reader {
      final private int BUFFER_SIZE = 1 << 16;
      private DataInputStream din;
      private byte[] buffer;
      private int bufferPointer, bytesRead;
  
      public Reader() {
          din = new DataInputStream(System.in);
          buffer = new byte[BUFFER_SIZE];
          bufferPointer = bytesRead = 0;
      }
  
      public Reader(String file_name) throws IOException {
          din = new DataInputStream(new FileInputStream(file_name));
          buffer = new byte[BUFFER_SIZE];
          bufferPointer = bytesRead = 0;
      }
  
      public String readLine() throws IOException {
          byte[] buf = new byte[64]; // line length
          int cnt = 0, c;
          while ((c = read()) != -1) {
              if (c == '\n') {
                  if (cnt != 0) {
                      break;
                  } else {
                      continue;
                  }
              }
              buf[cnt++] = (byte) c;
          }
          return new String(buf, 0, cnt);
      }
  
      public int nextInt() throws IOException {
          int ret = 0;
          byte c = read();
          while (c <= ' ') {
              c = read();
          }
          boolean neg = (c == '-');
          if (neg)
              c = read();
          do {
              ret = ret * 10 + c - '0';
          } while ((c = read()) >= '0' && c <= '9');
  
          if (neg)
              return -ret;
          return ret;
      }
  
      public long nextLong() throws IOException {
          long ret = 0;
          byte c = read();
          while (c <= ' ')
              c = read();
          boolean neg = (c == '-');
          if (neg)
              c = read();
          do {
              ret = ret * 10 + c - '0';
          } while ((c = read()) >= '0' && c <= '9');
          if (neg)
              return -ret;
          return ret;
      }
  
      public double nextDouble() throws IOException {
          double ret = 0, div = 1;
          byte c = read();
          while (c <= ' ')
              c = read();
          boolean neg = (c == '-');
          if (neg)
              c = read();
  
          do {
              ret = ret * 10 + c - '0';
          } while ((c = read()) >= '0' && c <= '9');
  
          if (c == '.') {
              while ((c = read()) >= '0' && c <= '9') {
                  ret += (c - '0') / (div *= 10);
              }
          }
  
          if (neg)
              return -ret;
          return ret;
      }
  
      private void fillBuffer() throws IOException {
          bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
          if (bytesRead == -1)
              buffer[0] = -1;
      }
  
      private byte read() throws IOException {
          if (bufferPointer == bytesRead)
              fillBuffer();
          return buffer[bufferPointer++];
      }
  
      public void close() throws IOException {
          if (din == null)
              return;
          din.close();
      }
  }
   class MultiTreeSet<E> {
  	TreeMap<E, Integer> freqTreeMap = new TreeMap<E, Integer>();
  	int size;
   
  	public MultiTreeSet() {}
   
  	public MultiTreeSet(Collection<? extends E> c) {
  		for(E element : c)
  			add(element);
  	}
   
  	public int size() {
  		return size;
  	}
   
  	public void add(E element) {
  		Integer freq = freqTreeMap.get(element);
  		if(freq==null)
  			freqTreeMap.put(element, 1);
  		else
  			freqTreeMap.put(element,freq+1);
  		++size;
  	}
   
  	public void remove(E element) {
  		Integer freq = freqTreeMap.get(element);
  		if(freq!=null) {
  			if(freq==1)
  				freqTreeMap.remove(element);
  			else
  				freqTreeMap.put(element, freq-1);
  			--size;
  		}
  	}
   
  	public int get(E element) {
  		Integer freq = freqTreeMap.get(element);
  		if(freq==null)
  			return 0;
  		return freq;
  	}
   
  	public boolean contains(E element) {
  		return get(element)>0;
  	}
   
  	public boolean isEmpty() {
  		return size==0;
  	}
   
  	public E first() {
  		return freqTreeMap.firstKey();
  	}
   
  	public E last() {
  		return freqTreeMap.lastKey();
  	}
   
  	public E ceiling(E element) {
  		return freqTreeMap.ceilingKey(element);
  	}
   
  	public E floor(E element) {
  		return freqTreeMap.floorKey(element);
  	}
   
  	public E higher(E element) {
  		return freqTreeMap.higherKey(element);
  	}
   
  	public E lower(E element) {
  		return freqTreeMap.lowerKey(element);
  	}
  }
   