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 math,sys
  #from itertools import permutations, combinations;import heapq,random;
  from collections import defaultdict,deque
  import bisect as bi
  def yes():print('YES')
  def no():print('NO')
  #sys.stdin=open('input.txt','r');sys.stdout=open('output.txt','w');
  def I():return (int(sys.stdin.readline()))
  def In():return(map(int,sys.stdin.readline().split()))
  def Sn():return sys.stdin.readline().strip()
  #sys.setrecursionlimit(1500)
  def dict(a):
      d={} 
      for x in a:
          if d.get(x,-1)!=-1:
              d[x]+=1
          else:
              d[x]=1
      return d
  def find_gt(a, x):
      'Find leftmost value greater than x'
      i = bi.bisect_left(a, x)
      if i != len(a):
          return i
      else:            
          return -1
  def main():
      try:
          n=I()
          l=list(In())
          mx=[]
          s=set([i for i in range(1,n+1)])
          for x in l:
              if x<=n and x in s:
                  s.remove(x)
              else:
                  if x&1==1:
                      mx.append((x//2,x))
                  else:
                      mx.append(((x//2)-1,x))
          if len(mx):
              mx.sort(key=lambda x:x[0])
          i=0
          s=list(s)
          s.sort()
          ans=0
          ok=True
          for i in range(len(s)):
              if s[i]<=mx[i][0]:
                  ans+=1
                  continue
              else:
                  ok=False
                  break
          if ok:
              print(ans)
          else:
              print(-1)            
  
      except:
          pass
          
  M = 998244353
  P = 1000000007
   
  if __name__ == '__main__':
      for _ in range(I()):main()
      #for _ in range(1):main()
  #End#
  
  #        ******************* All The Best *******************   #