# Kth Missing Positive Number

Given an array arr of positive integers sorted in a **strictly increasing order**, and an integer k.
*Find the *kth* positive integer that is missing from this array.*
**Example 1:**

**Input****:**
arr = [2,3,4,7,11],
k = 5
**Output****:** 9
**Explanation****:**** **The missing positive integers are [1,5,6,8,9,10,12,13,...]. The 5th missing positive integer is 9.

**Example 2:**

```
```**Input****:** arr = [1,2,3,4], k = 2
**Output****:** 6
**Explanation****:**** **The missing positive integers are [5,6,7,...]. The 2nd missing positive integer is 6.

**Constraints:**

1 <= arr.length <= 1000

1 <= arr[i] <= 1000

1 <= k <= 1000

arr[i] < arr[j] for 1 <= i < j <= arr.length

**Solution:**

```
class Solution {
public int findKthPositive(int[] arr, int k) {
Set<Integer> set = new HashSet<Integer>();
for(int a : arr)
{
set.add(a);
}
int start =1;
int Count = k;
while(Count>0)
{
if(set.contains(start))
{
start++;
}
else
{
start++;
Count--;
}
}
return start-1;
}
}
```