Given an unsorted array A[] consisting of n integers, write a program to find the length of the **longest consecutive sequence** of integers in the array.

**Problem Note **

- Your algorithm should run in
`O(n)`

complexity. - The consecutive numbers can be in any order.

**Example 1**

```
Input: A[] = [100, 4, 200, 1, 3, 2]
Output: 4
Explanation: The longest consecutive elements sequence is [1, 2, 3, 4]. Therefore its length is 4.
```

**Example 2**

```
Input: A[] = [20, 28, 12, 18, 23, 19]
Output: 3
Explanation: The longest consecutive elements sequence is [18, 19, 20]. Therefore its length is 3.
```