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

cases = int(input())
while cases:
    cases -= 1
    num = int(input())
    arr = list(map(int, input().split()))

    mn = min(arr)
    mx = max(arr)

    if mn == mx:
        print(-1)
    else:
        print(arr.index(mx)+1)
