Getting Timeout on submitting this code, can some1 help ?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication1
{
class Program
{

    static void Main(string[] args)
    {

        String[] ans;
        
        int noOfTC = Int32.Parse(Console.ReadLine());
        String[] s1= new String[noOfTC];
        String[] s2 = new String[noOfTC];
        int[] L = new int[noOfTC];
        
        for (int i = 0; i < noOfTC; i++)
        {
            s1[i] = Console.ReadLine(); 
            s2[i] = Console.ReadLine();
            L[i] = Int32.Parse(Console.ReadLine());               
        }

        ans = new String[noOfTC];
        for (int i = 0; i < noOfTC; i++)            
            ans[i] = start(s1[i], s2[i], L[i]);

        for (int i = 0; i < noOfTC; i++)
            Console.WriteLine(ans[i]);
                    


    }

    private static String start(String s1, String s2, int L)
    {
        if (s1.Length > s2.Length)
        {
            String t = s1;
            s1 = s2; s2 = t;
        }

        String testStr, temp = "";
        int count = 0, subCount = 0;
        int k = 0;

            while (k < L)
            {
                k++;
                for (int i = 0; i <= s1.Length-k; i++)
                {
                    testStr = ""; subCount = 0;                        
                            testStr = s1.Substring(i, k );                                
                            subCount = isSubStrFound(s2, testStr);
                             count += subCount;                        
                }
                temp += count + " ";
                count = 0;
            } 


        return temp;
    }



    public static int isSubStrFound(string text, string pattern)
    {            
        if (!text.Contains(pattern))
            return 0;
        else
            return 1;
    }
}

}

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