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.io.*;
  public class A1618 
  {
  	static int md=(int)(1e9);
  	
  	public static void process()throws IOException
  	{
  	   int n=I();
  	   int a[]=Ai(n);
  	   int c=0;
  	   HashSet<Integer> arr=new HashSet<Integer>();
  	   for(int i=0;i<n;i++)
  	   {
  		   if(a[i]<=n && arr.contains(a[i])==false){
  			   arr.add(a[i]);
  			  continue;
  		   }
  		   else
  		   {
  			   a[i]=a[i]%(a[i]/2+1);
  			   c++;
  		   }
  	   }
  	   sort(a);
  	   boolean flag=false;
  	for(int i=0;i<n;i++)
  	{
  		if(a[i]>=i+1)
  		{
  			continue;
  		}
  		else
  		{
  			flag=true;
  			break;
  		}
  	}
  	if(flag)
  	{
  		pn(-1);
  	}
  	else
  	{
  		pn(c);
  	}
  			
  	}
  	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;
  		}
  	}
  	static void sort(int[] a) {
  		int n = a.length;
  		Random r = new Random();
  		for (int i = 0; i < a.length; i++) {
  			int oi = r.nextInt(n);
  			int temp = a[i];
  			a[i] = a[oi];
  			a[oi] = temp;
  		}
  		Arrays.sort(a);
  	}
  	static FastReader sc = new FastReader();
  	static PrintWriter out = new PrintWriter(System.out);
  	static void pn(Object o){out.println(o);out.flush();}
  	static void p(Object o){out.print(o);out.flush();}
  	static void pni(Object o){out.println(o);System.out.flush();}
  	static int I() throws IOException{return sc.nextInt();}
  	static long L() throws IOException{return sc.nextLong();}
  	static double D() throws IOException{return sc.nextDouble();}
  	static String S() throws IOException{return sc.next();}
  	static char C() throws IOException{return sc.next().charAt(0);}
  	static int[] Ai(int n) throws IOException{int[] arr = new int[n];for (int i = 0; i < n; i++)arr[i] = I();return arr;}
  	static String[] As(int n) throws IOException{String s[] = new String[n];for (int i = 0; i < n; i++)s[i] = S();return s;}
  	static long[] Al(int n) throws IOException {long[] arr = new long[n];for (int i = 0; i < n; i++)arr[i] = L();return arr;}
  	static void dyn(int dp[][],int n,int m,int z)throws IOException {for(int i=0;i<n;i++){ for(int j=0;j<m;j++){ dp[i][j]=z;}} }
  	
  //	*--------------------------------------------------------------------------------------------------------------------------------*//
  	
  	public static void main(String[] args)throws IOException{try{boolean oj=true;if(oj==true)
  	{PrintWriter out=new PrintWriter(System.out);}
  	else
  	{out=new PrintWriter("output.txt");}
  	long T=L();while(T-->0)
  	{
  	process();
  	}out.flush();out.close();}catch(Exception e){return;}}}
  //*-----------------------------------------------------------------------------------------------------------------------------------*//
  	