#include <iostream>
#include <fstream>
#include <string>
#include <deque>
using namespace std;
int main(){
    deque<char> d;
    int n,k, c=0;

    string s;
    ifstream f("alibaba.in");
    ofstream g("alibaba.out");

    f >> n >> k>> s;
    d.push_back(s[0]);
    for (int i = 1; i < n; i++){
        while (d.size() > 0 && c < k && s[i] > d.back()  ){
            d.pop_back();
            c++;
        }
        if (d.size() < n-k)
            d.push_back(s[i]);
    }
    while(d.size() > 0){
        g << d.front();
        d.pop_front();
    }
    return 0;
}