#include <string>
#include <iostream>
#include <fstream>
using namespace std;
int Count(const std::string& str, const std::string& sub)
{
    if (sub.length() == 0) return 0;
    int count = 0;
    for (size_t offset = str.find(sub); offset != std::string::npos;
	 offset = str.find(sub, offset + sub.length()))
    {
        ++count;
    }
    return count;
}
int main() {
    fstream fin("substr.in",ios::in);
    fstream fout("substr.out",ios::out);
    int k,n;
    fin >> n >> k;
    string s="";
//    cout << n;
    for (int i=1;i<=n;i++)
    {
        char x;
        fin >> x;
        s+=x;
    }
//    cout << s;


    int maxxx;

    for (int i=0;i<s.size();i++)
    {
        for (int j=i;j<s.size();j++)
        {
           string temp = s.substr(i,j);
           if (temp.size()>1)
           {
                int n = Count(s,temp);
//                cout <<temp<<" "<< n <<'\n';
                if (n>=k)
                {
                    maxxx = temp.size();

                }
           }


        }
    }
    fout << maxxx;
}