Given a sorted integer array `arr[]`

of `n`

elements and a target value `k`

, write a program to search `k`

in `arr[]`

.

**Problem Note**

- If
`k`

exists, then return its index, otherwise, return -1. - You may assume that all elements in

are unique.`arr[]`

**Example 1**

```
Input: arr[] = [1, 5, 6, 7, 9, 10, 50], k= 9
Output: 4
Explanation: 9 exists in arr[] and its index is 4.
```

**Example 2**

```
Input: arr[] = [1, 5, 6, 7, 9, 10, 50], target = 20
Output: -1
Explanation: 20 does not exist in arr[] so return -1.
```