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 _ in range(t):
    n = int(input())
    mas = list(map(int, input().split()))
    mx = max(mas)
    fb = 0
    for i in range(n):
        if mas[i] == mx:
            if (i - 1 >= 0 and mas[i - 1] < mas[i]) or (i + 1 < n and mas[i + 1] < mas[i]):
                print(i + 1)
                fb = 1
                break
    if not fb:
        print(-1)
