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

test_cases = int(input())
for _ in range(test_cases):
    n = int(input())
    a = [10**10] + list(map(int, input().split())) + [10**10]
    max_elem = -1
    pos = -1
    for i in range(1, n + 1):
        if (a[i] > a[i - 1] or a[i] > a[i + 1]) and a[i] > max_elem:
            max_elem = a[i]
            pos = i
    print(pos)