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()))
    idx_ = -1
    max_ = 0
    arr = [1000000001] + arr + [1000000001]
    for i in range(1, n+1):
        flag = arr[i] > arr[i-1] or arr[i] > arr[i+1]
        if arr[i] >= max_ and flag:
            max_ = arr[i]
            idx_ = i
    print(idx_)
    
