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 sys
  tokens = ''.join(sys.stdin.readlines()).split()[::-1]
  
  def next(): return tokens.pop()
  def nextInt(): return int(next())
  def nextFloat(): return float(next())
  def getIntArray(n): return [nextInt() for _ in range(n)]
  def getFloatArray(n): return [nextFloat() for _ in range(n)]
  def getStringArray(n): return [next() for _ in range(n)]
  
  
  testcase = True
  def solve(testcase = 1):
      N = nextInt()
      A = sorted(getIntArray(N))[::-1]
  
      S, R = set(), []
      for itr in A:
          if 1 <= itr <= N and itr not in S:
              S.add(itr)
          else:
              R.append(itr)
  
      k = 0
      for s in range(N, 0, -1):
          if s in S: continue
          if s * 2 < R[k]:
              k += 1
          else:
              print(-1)
              return 
      print(N - len(S))
      pass
  
  
  if testcase is None:
      testcaseCount = 1
      while tokens:
          solve(testcaseCount)
          testcaseCount += 1
  else:
      testcaseCount = nextInt() if testcase else 1
      for tc in range(testcaseCount):
          solve(tc + 1)
      assert not tokens