1
3
5 3 4
 6
5
5 3 4 4 5
3
1 1 1
5
4 4 3 4 4
5
5 5 4 3 2
3
1 1 2
5
5 4 3 5 5
 1
3
10 1 5

1
 1
-1
2
2
3
1
 1

t = int(input())
res = []
for i in range(t):
  kol = int(input())
  a = [int(i) for i in input().split()]
  a = sorted(a)
  if a[len(a)-1] == a[0]:
    res.append(-1)
  else:
    res.append(len(a)-1)
for i in range(len(res)):
  print(res[i])