1394\. Find Lucky Integer in an Array

Easy

Given an array of integers `arr`, a **lucky integer** is an integer that has a frequency in the array equal to its value.

Return _the largest **lucky integer** in the array_. If there is no **lucky integer** return `-1`.

**Example 1:**

**Input:** arr = [2,2,3,4]

**Output:** 2

**Explanation:** The only lucky number in the array is 2 because frequency[2] == 2.

**Example 2:**

**Input:** arr = [1,2,2,3,3,3]

**Output:** 3

**Explanation:** 1, 2 and 3 are all lucky numbers, return the largest of them.

**Example 3:**

**Input:** arr = [2,2,2,3,3]

**Output:** -1

**Explanation:** There are no lucky numbers in the array.

**Constraints:**

*   `1 <= arr.length <= 500`
*   `1 <= arr[i] <= 500`