# include <fstream>
# include <string>
# include <map>
# define DIM 16484
using namespace std;
ifstream fin("substr.in");
ofstream fout("substr.out");
string s;
map<string,int> m;
char ch[DIM];
int n,k,step,i,j;
bool val(int q){
    for(i=1;i<=n;i++){
        s.insert(s.end(),ch[i]);
        if(i>=q){
            if(!m.count(s))
                m[s]=1;
            else
                m[s]++;
            if(m[s]==k){
                m.clear();
                s.clear();
                return 1;
            }
            s.erase(s.begin());
        }
    }
    s.clear();
    m.clear();
    return 0;
}
int sol(){
    for(step=1;step<=n;step*=2);
    for(j=0;step;step/=2)
        if(j+step<=n&&val(j+step))
            j+=step;
    return j;
}
int main () {
    fin>>n>>k>>ch+1;
    //fout<<sol();
    for(;;);
    return 0;
}