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 s in[*open(0)][2::2]:
 a=*map(int,s.split()),;n=len(a);m=max(a);i=j=a.index(m)
 while j<n and a[j]==m:j+=1
 print(i or j<n and n-j or -1)