#### You are given an array consisting of N non-negative integers, and two non-negative integers K and M, your task is to find a pair of indices(say i and j) from the array such that ‘i’ ≠ ‘j’, |Ai-Aj| <= M, and |i-j| <= K, where |a-b| represents the absolute value of a-b.

#### Note:

```
1) The array may contain duplicate elements.
2) The size of the array is at least 2.
3) The given array follows 0-based indexing so 0 <= i,j< N.
4) It is guaranteed that there exist at least one such pair of indices.
```

```
The first line of the input contains an integer T denoting the number of test cases.
The first line of each test case contains three space-separated integers N, K, and M, as described in the problem statement.
The second line of each test case contains N space-separated integers, representing the elements of the array.
```

```
You just need to find the pair of indices(i and j), and if the pair returned satisfies the given condition, the output will be shown as “valid”, else the output will be shown as “invalid”.
```

##### Note:

```
You do not need to print anything, it has already been taken care of. Just implement the given function.
```

##### Constraints:

```
1 <= T <= 50
1 <= N <= 10^4
1 <= K <= N
1 <= M <= 10^9
1 <= arr[i] <= 10^9
Time Limit: 1sec
```

##### Sample Input 1:

```
1
4 1 2
2 4 6 8
```

##### Sample Output 1:

```
valid(one of the possible answers is 0 1).
```

##### Explanation for sample input 1:

```
Difference between the elements at index 0 and 1 is 2 which is at most M, and also the difference between the indices is 1 which is at most k.
```

##### Sample Input 2:

```
1
3 2 2
2 3 4
```

##### Sample Output 2:

```
valid(one of the possible answers is 0 2).
```

##### Explanation for sample input 2:

```
Difference between the elements at index 0 and 2 is 2 which is at most M, and also the difference between the indices is 2 which is at most k.
```