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 i in range(t):
  a=[int(x) for x in input().split()]
  s=0
  q=0
  if len(set(a))==1:
    print(-1)
  else:
    for i in range(len(a)):
      if s<a[i]:
        q=i
        s=a[i]
  print(i)