#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-9;
const int MOD = 1e9 + 7;
template <class T>
inline T my_min(T a, T b) {
  return a < b ? a : b;
}
template <class T>
inline T my_max(T a, T b) {
  return a > b ? a : b;
}
template <class T>
inline void my_swap(T& a, T& b) {
  T tmp = a;
  a = b;
  b = tmp;
}
template <class T>
inline T my_abs(T a) {
  return (a > 0 ? a : -a);
}
const int max_size = 4e5 + 5;
string str;
int n, k;
struct dat {
  int pos;
  char c;
  dat() {}
  dat(int p, char ch) : pos(p), c(ch) {}
  bool operator<(const dat& x) const { return c < x.c; }
} d[max_size];
vector<dat> v;
bool cmp(dat x, dat y) { return x.pos < y.pos; }
int main() {
  cin >> n >> k >> str;
  for (int i = 0; i < n; i++) v.push_back(dat(i, str[i]));
  stable_sort(v.begin(), v.end());
  v.erase(v.begin(), v.end() - (n - k));
  sort(v.begin(), v.end(), cmp);
  for (int i = 0; i < v.size(); i++) cout << v[i].c;
  cout << "\n";
  return 0;
}
