[C#] problem related to vowels and consonants

Madhan has been a given a problem by his brother Jayi .The problem is related to strings.
Now he gives Madhan a long String S which consists of lowercase English Alphabets and wants him to tell the minimum size of substring such that all the substrings of that size in S have at least K Consonants(Non-vowels) in them.
If none of the subArray size satisfy the above condition ,return -1.

Input Format
Your function contains two arguments a String S and an Integer K.
First line of input contains a String S.
Second line of input contains an Integer K.

Constraints
1 <= |S| <= 100000
1 <= K <= 10000

Output Format
You must return an Integer denoting the answer to the problem.

Sample TestCase 1
Input:

ritikisagoodboy
4


Output:

9

Explanation

All substrings of length 9 have greater or equal to 4 non-vowels in them and this is the minimum size that we can have.
In substring of size 8 .. the substring ''ikisagoo'' has only 3 non-vowels therefore it violates the condition.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class CandidateCode {

 static int Consonant(string input1,int input2)
    {
    	//code to be written 
    }

static void Main(String[] args) {
    int output;
    string ip1;
    ip1 = Console.ReadLine();
    int ip2;
    ip2 = Convert.ToInt32(Console.ReadLine());
    output = Consonant(ip1,ip2);
    Console.WriteLine(output);
    }