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())
    arr = list(map(int, input().split()))

    res = -1
    maxVal = 0

    if n == 1:
        print(1)
    else:
        for i in range(n):
            if arr[i] > maxVal:
                if i == 0:
                    if arr[i] > arr[i + 1]:
                        maxVal = arr[i]
                        res = i + 1
                elif i == n - 1:
                    if arr[i] > arr[i - 1]:
                        maxVal = arr[i]
                        res = i + 1
                else:
                    if arr[i] > arr[i + 1] or arr[i] > arr[i - 1]:
                        maxVal = arr[i]
                        res = i + 1

    print(res)
