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 = 1
t = int(input())
for _ in range(t):
    n = int(input())
    arr = list(map(int, input().split()))
    mx = max(arr)
    result = -1
    for i in range(n-1):
        if mx == arr[i] and arr[i] > arr[i-1]:
            result = i + 1
    print(result)
