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())
for test in range(t):
   n = int(input())
   a = list(map(int, input().rstrip().split()))
   m = max(a)
   flag = -1
   for i in range(n-1):
      if a[i] == m and a[i+1] != m:
         flag = i+1
   for i in range(n-1, 0, -1):
      if a[i] == m and a[i-1] != m:
         flag = i+1
   print(flag)