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

for _ in range(int(input())):
    input()
    aqua = list(map(int, input().split()))

    max_aqua = max(aqua)
    if min(aqua) == max_aqua:
        print(-1)
    else:
        # точно есть доминирующая
        min_index = aqua.index(min(aqua))

        max_r = max(aqua[min_index:])
        if max_aqua == max_r:
            print(aqua[min_index:].index(max_aqua) + min_index + 1)
        else:
            print(min_index - aqua[:min_index][::-1].index(max_aqua) + 1)
