First Repeating Element
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  Difficulty: Easy   Marks: 2

Find the first repeating element in an array of integers, i.e., an element that occurs more than once and whose index of first occurrence is smallest.

Input :
The first line contains an integer T denoting the total number of test cases. In each test cases, First line is number of elements in array N and second its values.

Output:
In each separate line print the index of first repeating element, if there is not any repeating element then print “-1” (without quotes). Use 1 Based Indexing.

Constraints:
1 <= T <= 500
1 <= N <= 106
0 <= Ai <= 106

Example:
Input:
1
7
1 5 3 4 3 5 6

Output:
2

Explanation: 
Testcase 1: 5 is appearing twice and its first appearence is at index 2 which is less than 3 whose first occuring index is 3.

** For More Input/Output Examples Use 'Expected Output' option **

Contributor: JASPREET Singh
Author: abhiraj26


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